I would like to but some add-ons that actually produce HP. Every article I read says the exhaust is where I can get it. Has anyone installed a set of headers, high-flow cats and aftermarket mufflers and then had the car on a dyno to see what it produced?? Can I get good HP on a stock 4.6 with these add-ons and not be mad about the cost??

 

There is no real gain in anything exhaust for the 4.6 2V. The most gain is from an offroad X pipe. Headers are very bad on the cost vs. gain scale. There's better ways to get HP for the money than exhaust after you get past the offroad X.

 

biggest gain power wise in the exhaust on a mostly stock car is from a off road mid pipe. I dropped 3 tenths with no other mods. Just added a o/r H-pipe and went to the track on wed without it, went back on Friday and it dropped a solid 3 tenths and picked up almost 2mph. Same 60' and similar weather conditions.

But long tube headers, o/r mid pipe, and catback will make the car faster for sure.

 

yeah, absolutely. as said, the biggest gain will be from ditching all those cats on the car and going with a off road midpipe. If you go with longtubes, off road midpipe, and catback it will really give the car a nice sound and some performance gain. most people dont do exhaust for huge hp/tq gains, but more for the sound and when you do get some more serious mods they help the motor breathe

 

+1 for this man.

 

I beg to differ. I've had long tubes and shorties, both w/ an x-pipe with 2 Magnaflow cats. The difference was night and day, which I truly miss the long tubes. If you want the best bang for your buck, full exhaust w/ long tubes. Mid-pipes don't really add that much, as well as mufflers. However, a good set of long tubes can add 20 hp, stock. Add cams and the gains get better. As for price, do it yourself to save costs. My Hooker set-up, w/ the off-road x was $700 and it netted enough power as cams, but unlike cams, improves the entire power band (instead of shifting it).

As a comparison, I went from getting 26 mpg highway, doing 90 mph w/ long tubes to getting that w/ my shorties doing 70-75 mph. As for suburb driving, I went from 21 mpg to 19-20 mpg, respectively.

 

Hey NCredneck, where ya' been for 2 years.................forgot your password?

 

You can beg to differ all you want, but the dyno doesn't lie. On a mild 4.6, the most I've ever seen actually proven on the dyno by a set of headers came from a set of American Racing headers, which gained 12rwhp, and cost over $1200 without the midpipe. Kooks were close, BBK and MAC were 8-10rwhp average. Of course, once you are supercharged, the gains are exponential, and you'll see more. But the original poster was looking for quick horsepower. You are not going to see 20rwhp gains from ANY header system on a mild 4.6.........period. There also is no significant shift in the powerband with any of them.

In comparison, my UPR off-road X gave me 6rwhp with no other changes, proven on the dyno. 6rwhp for $150 vs. 8-10rwhp for $700ish vs. 12rwhp for $1200....... You do the math. You can't even feel or measure that 2rwhp difference. Well, you may be a little faster, because of the $550 you don't have in your wallet anymore, I'm sure that weight makes more of a difference than the minor HP gains. There are much better ways to spend that extra $550 that will give you significantly more HP than headers. People want headers just to say they have headers, and they think they feel the gain because they want to, since they spent the money.

Just for the record, I have an $1800 set of American Racing Headers with catted X pipe sitting in my shop for my car. I have an extremely bad back, 2 surgeries later, and I'm not able to twist and climb under my car for a long enough time to install them myself. So, the average install cost around here for a set of longtubes on a New Edge is $400, because it is a pain. So that brings my total cost for these headers to around $2200 after installation. For $2200, I could have bought a used supercharger, and picked up a lot more than 12-15rwhp, and installed it myself in the garage.

Bottom line: The stock exhaust on the 4.6 GT is fairly good. The only real restriction is the 4 catalytic converters. Using an offroad X or H takes care of that problem. I feel that on the list of horsepower vs. gains, headers are very very very low on the list. If I felt that the headers were going to give me enough gain to warrant the cost, mine would have been on 6 months ago when I bought them. My goals then were a bit more extreme than they are now, so I bought them. Once I get to the point to where I put a tubular K Member on my car, or do a headswap, they'll go on at that time, since either way would be easier, and make it worth the hassle. I'm not anti-header, I just feel that on a mild car, the cost and hassle don't justify the gains vs. other mods for the same cost.

Spend your money starting out on things that will actually make a big difference, like gears. That should have been the first thing I did, not 10 months later. Gauge your mods smartly, and consider cost vs. real world gains, not what the manufacturer claims, and you'll be a lot happier with your progress.

 

^ couldnt agree more. your biggest gain is from freeing up all the cats on the stock midpipe. there is no way you are picking up 20rwhp just from longtubes on a bolt on GT. not happening

 

I just put on an O/R H pipe and let me tell you. You will get more power then you think.

 

Once you are past the bullshit bolt on's and actually do cam's or ported heads or nitrous or forced induction. Then long tubes really help out the power band. **** Jayc and me before he had his cams installed had very similar mods only he had long tubes and I don't and he pushes around 25-35rwhp (depending on how much he is spraying) more then my car. I know its not a fair comparison being different cars, but it shows you there is power there.

I agree though for a car with little mods, mid pipe is a good bang for the buck. It was my first mod because I knew it would make a difference at the track where it matters. Plus you drop some weight over having all those catalytic converters on there.

 

I'm sure you will see that the long tubes gained much more throughout the curve, as that's what long tubes do. On the other hand, I bet the mid-pipe by itself lost power in the lower rpm bands. In addition, that may be just that result. I've seen numbers in the upper teens for a stock engine (minus CAI and intake elbow which have marginal affects).

In addition, my numbers don't lie. My drop in mileage from going from LTs to shorties is proof that there is a significant loss in power, enough so to decrease the mileage. And you may say I didn't notice it but unless you drove my car, you wouldn't know. Besides, a 2 hp difference wouldn't be noticed at the pump, especially a 2 mpg difference.

As for price, my Magnaflow catted x cost me $600. My LT set-up minus cats cost me $700. Add $550 for cats. The price difference wasn't that much and gaining enough juice to not only feel a serious difference but also notice it at the pump is worth it.

That's why for the street, I think LT's are worth it. They increase power by not sacrificing the low end (they do it by raising the torque curve, not just by shifting it to the right like cams do) and if you aren't afraid to drop the k-member, are easy to install. While they shine better on a modified car, a mid-pipe is more of a waste on a stock car. A mid-pipe by itself will not improve the bottom end (and will most likely hurt it) and for a street car, is not a good choice as you'll never benefit from the gains up top.

Remember, a car on the street needs to increase power by not sacrificing the low end. The best way to do this is with a set of long tubes, as they accomplish this.

 

Did you take said car to the dyno after each setup? If not, your "results" are not valid in the least. The butt-dyno is the most inaccurate machine ever known in the car world.

All of my data is based on numerous testing on numerous cars throughout the life-span of the 4.6 engine. Even before it was put into a Mustang. So one person's opinion is just that to me, an opinion. I've seen it over and over again.

I will stand on the highest mountain and scream it everytime someone talks about putting headers on a mild 4.6, PUT YOUR MONEY TOWARDS SOMETHING THAT WILL ACTUALLY GIVE YOU PROVEN AND TESTABLE GAINS!!!!!!!

Once you've done the rest of the bolt-ons, before or at the same time that you actually go into the cylinder heads is the time to do headers, you simply don't need them, or get enough gains out of them until that time to quantify the expense.

 

Hey i hate to sound like a dumbass, but whats the real difference between offroad pipes, long/shorty headers and etc? I would look in the exhaust sticky but i cant seem to find it Also WTH do catalytic converters do? I dunno why but exhaust has been my least interested subject of my mustang.

 

The butt dyno is inaccurate, but if you notice a difference, then it's large enough to notice. Usually 5 or more. Plus, again, the pump doesn't lie. The fact that my mileage dropped going to shorties demonstrates a decent loss in power. 2-3 hp isn't going to cause a 2 mpg drop.

Now, you have results, but were they done during the same weather conditions? Humidity, air temperature, and pressure can all affect power numbers. Enough so that people get the best 1/4 mile times in the winter, by tenths of a second. Testing the long tube car on a lower pressure day than the mid-pipe only car (or even a difference of 10°) can have significant results. That's why a controlled environment is so important when comparing numbers. The numbers I provided were by running long tubes for 2 years, and shorties for almost a year. My highway mileage I listed was the average from driving on the same road, from the same point a-b, in all different weather conditions. Suburb is a bit different, as it's hard to maintain the same acceleration rates and the same speeds but what I gave was a range what I usually get.

And again, average and peak numbers are not good numbers to use on a street car. Remember, a street car is rarely going to hit anything more than 3,000 rpm, so one should concentrate on making the most power from idle to 3,000 rpm. I guarantee you that your dyno results showed a drop in power in that rpm range for the off-road pipe, going from stock. On the other hand, I guarantee that the long tubes showed an increase
as again, a properly designed set of headers will increase across the entire rpm range, without shifting it to the right.

Unless you are going to be hitting high rpms, you are better off stock over an aftermarket mid-pipe, as you'll make more power stock. However, long tubes will make more juice down low and for a street car, is a better power adder than just a mid-pipe.

 

If that's what you have to tell yourself to justify the money you spent, then that's fine.

I have no problem admitting that I wasted money on headers when it could have went towards things that actually would have shown more improvement, and to try to keep people from making the same mistake I did.

 

I'm not justifying wasted money, because it wasn't.

Again, for the vast majority of us, we will never see anything past 3,000 rpm except on the rare occasion. That is why it makes absolutely no sense to put money into parts that not only increase on the top end, but at the same time, hurt the low end. This is why I think lopey cams are retarded on the street, especially one without long tubes, as the power curve is shifted too far to the right. Just adding a mid-pipe is not worthy for the street, as I mentioned before, because it sacrifices power below 3,000 rpm to make it up top. No point in spending money on a part that will actually decrease power in your useable rpm range.

Now as for dyno numbers, since I happen to be home now, I do have some from my Building Ford Horsepower Book. Test 1 in chapter 9 is Hooker Super Comps (which is what I had) being tested on a stock NPI engine. With stock manifolds, it made 269/319 (engine was run w/ straight pipes and no accessories). The Hooker Headers made 307/345. Even I think these numbers were a bit optimistic but remember, this was an engine dyno, so it was sucking dry air. Add to it that what I gave out as a guess was half of that, that seems more reasonable. In addition, it is important to note that the headers did not shift the torque curve to the right, but instead up, creating more average torque and power.

As a comparison, test 3 was a set of Kooks headers on a stock PI engine (no accessories, straight pipes) and that made 287/332. The headers made 298/345. Note that the Kooks headers added less power since the Hookers are more race oriented and the Kooks are more street oriented. In addition, all peak numbers happened at the same rpm, which means the entire torque curve moved up again, creating more power throughout the entire rpm band.

As for the mid-pipe, Ford Muscle did an x-pipe install and while it made 6-8/10 up top, anything below 3,000 rpm had losses or no increase.

This is why for a street car, even a stock one, long tubes are worth it, as they increase power in the entire powerband, from idle to redline. On the other hand, just a mid-pipe will only increase the top end, sacrificing the low end. I guess if your state is strict on emissions, a catted mid-pipe is the way to go but if you aren't lazy and want to cough up the couple extra bucks, it is worth it.

Call me a lier saying that I wasted my money and I can't tell the difference in power between shorties and long tubes, but what I provided is my personal experience from running both systems for at least a year or more. If anything, I only regret choosing Hookers and not doing it right the first time (coated, locking bolts, good gaskets, etc.). If I had to do it again, I'd do Kooks, as they fit better and would still be running them. I'd sacrifice a bit in power but the headaches the Hookers gave me made me downgrade.

 

I never called you a liar, or said you wasted your money. I'm simply trying to stress my point that headers are not a good modification for a mild 4.6, unless you've done everything else, or are setting yourself up for the future. However, if you don't have the tools or the place to do it, the install cost on them makes them really crappy money vs. horsepower mods, especially as a first mod. There are tons and tons of Mustang making over 400rwhp and 400rwtq on stock manifolds, so they definately aren't much of a restriction to begin with.

I have a history of saying that any mod that you do to the exhaust of a stock 4.6 Mustang is simply for the sound, not for serious performance until you either do heads and cams, or add a supercharger. It's simply not worth the money until then.

 

Longtubes were my last bolt-on........as they should be

 

My car dynoed 260rwhp with full exhaust(mid length headers), o/r x pipe and, slp catback, and a bbk intake through an auto... I would say the headers netted me some nice gains since stock auto's dyno 220rwhp.

 

First of all...don't spend $1200 on headers. Man search the forums and find someone that bought them but decided not to install them or get a set used. I picked up a set of BBK longtubes and o/r xpipe new for $425. Of course it helps if you know someone that can install them or you can do it yourself. I would never drop $1200 on headers and xpipe that's plain ridiculous. You could search around and find a procharger for a near $800 more...then you'd be close to 400hp.

 

Then that was my fault for misreading. I apologize for then.

Now, I understand your point but my philosophy, as you've seen, is to make the most power on the street, in a streetable rpm range. However, keep in mind that the install really isn't that bad. I've done it both w/ and w/o the k-member in place and the difference was a PITA to ease. I did it in 2 days w/ the k-member off, where-as with it in place, it was nearly impossible. If you can do a clutch job, this isn't anything more difficult (and I think easier). Now while many Mustangs run stock manifolds at high horsepower levels, there is a lot left at the table. It's not so much as manifolds are restrictions, but that they do not provide the vital exhaust tuning to enhance scavenging. That's why header design is so important to squeeze out as much power as possible. The examples w/ the Hooker and Kooks headers show this, as Hooker went for more power only and Kooks power but good fit as well.

Increasing power is all about trade-offs. That's why I think headers are worth it always, as they trade nothing for more power, except time and cash, like any other part.

 

And BBK headers are pure crap compared to American Racing or Kooks. Just look at them side by side, and you can see where the money goes. Better materials, better fitment (no crimped pipes for clearance like the BBKs), and better welds. Basically, the American Racing and Kooks will outlast the car, where the BBK's are for people who just want to say they have headers.

The BBK's are probably last on my list of headers I would spend my money on. The American Racing and Kooks are at the top. If I had to buy a set of the more inexpensive headers, I'd go with MACs, they at least seem to be decently put together, and no crimped tubes.

I take that back, the FlowTechs are last on my list, those things are complete garbage.

 

I understand your point completely, but to recommend them as one of the first mods to do will make someone crazy........

 

Hence why I'm a strong proponent on removing the k-member. I tried it with it in place and I had no spring break as a result.

 

a little advice... steer clear of headers until you don't have anything left to waste money on. The Dollar:HP ratio is really shitty with them. Yes, they will free up a little hp but for the grand plus you can get one badass nitrous kit or any of a series of other mods that will make your ride more fun.

If you want sound, keep it basic, cat-back and x/h pipe.

After all I've done and all the money spent I'd just put cobra brakes, a blower and some good suspension on it and stop there if I had it to do again.

 

I never said BBK headers were superior to American Racing or Kooks. Just wanted others to see you don't have to spend $1200 on LT's. The HP to $$ ratio is higher with the BBKs than a set of $1200 LT's. Hell someone could buy a set of Macs or BBKs plus 410s for the price of those.

 

The HP to $ ratio may be better initially, but when the BBKs start leaking because of the mild steel and crappy welds, paying to have them taken off and rewelded at the flange, and then reinstalled makes the cost a lot more. I've seen 2 pair of BBKs that leaked from the welds straight out of the box, brand new, because the weld quality was crap.

 

Never mind their method to clearance the driver side header...

 

You mean the tubes that are flattened halfway shut? That's a lack of engineering or caring on BBK's part. If everyone else had to crimp the tubes shut to clear, I could understand, but since they're the only ones that do that, it shows they weren't willing to take the time to design a header that actually fits well.

I would definitely buy MAC headers if I was in the market for a more inexpensive set, and leave the BBKs where they sit.