Hey everyone,

The only installed part I have on my 2004 mustang gt is K&N intake.

I really want to add extra hp but I'm not sure what I should purchase first.

Magnaflow x-Pipe
Magnapack CatBack
$229-Accufab Plenum for 4.6L-http://www.americanmuscle.com/ac70plfor4.html
$149.99-3.33" s/c pulley-http://www.americanmuscle.com/bbk-aluminum-pullies-2001-2004.html
Questions:
1. If I purchase the X-Pipe it won't change the sound but it will improve the hp?
2. If I purchase the CatBack it won't improve performance but it will improve the sound?
3. Accufab Plenum for 4.6L, is it worth buying this? Should I have other upgrades before purchasing this? Same question for the Pulley.

What would you do? Pulley + Accufab Plenum or would you choose the x-pipe and then buy the catback afterwards or vice versa.

Also when does the car require a retune, and are the tuner chips just for manually tuning so you don't have to take a trip to the dyno?

I'm on a limited budget right now.


Thanks for the help, sorry for all the noob questions.

 

I am sure I am not the only one who will tell you this, but the first thing to really get the car going off the bat is gears. If an automatic go 4.10's (I did 3.73's due to some other considerations in my auto) and 3.73's for a manual. I didn't have the advice you will get when I began my mustang 5 years ago. I spent tons of money on the parts which were available for the 4.6 such as bigger MAFS, fenderwall intakes, pulleys, etc. Gears should be first I think. After that, it is subjective, but a full exhaust change, then throttle bodies and intake parts and cams. Once you get the car to a point where you feel ready to spend the money and get it dynoed and tuned. A good tune and gearing can really wake a car up and tighten up the cars manners. The best advice is to get a good feel for what you hear and are told and make the "best" decision for you on your car.

 

The x-pipe will def change the sound, maybe slightly raspier and a slight but probably unnoticed power increase. The x -pipe and catback together might give you a little noticable hp. I would guess 10-15hp.

The Accufab plenum used in connection with larger throttle body ,70mm, in your case might add a few hp also. The Accufab def seems to get the best reviews and test results.

I personally do not like underdrive pullies and have no experience with them.

You car could be tuned right now even if it was completely stock and you will see some added horsepower. Remember that the factory tunes your car for mostly fuel efficiency and emissions. So getting it tuned will increase your hp. This to be the most effective would be on a dyno. Mail order tunes are okay sometimes but every car is a little different and mail order tunes cannot factor these differences in. Most of the time a chip or handheld tuner is fine till you do major modifications. Turbo, Blower, etc..

Out of your choices I would start with the catback. Quick easy to install and a great sounding result.

I would start with rear end gears.
FRPP 3.73's or 4.10's.
Even though you will not get an actual hp increase it will def. feel like you have.

 

By the way, I have a Professional Products Plenum with less than 500 miles on it, if your interested. I have a strut tower brace on my stang and with this intake plenum and the brace, they cause the cold air intake not to fit. I personally am not a believer just yet the plenum is the way to go until the car is modified and then you top it off with the plenum. I am likely just going to port and polish my current plenum.

 

Save up and buy it all at once. Then you will notice a difference. But if you cant hold yourself, by some gears.

If you are just looking for some cheap, efficient power then go with nitrous.

 

Thanks for the friendly replies guys.

I think I'll try and get those gears you weren't the only one to tell me to start with that.

I wanted to do the pulley and plenum because together they are the same cost as the catback and it seems I would get more hp out of it for the price at this time.

I still haven't made up my mind its either those 2 or the catback.. I'm definitely getting those gears thought. My cars manual.


Could I install those gears, as well as the plenum and pulley? I did install my intake but I have little to no knowledge of cars besides the basics.

 

No,You won't be able to install the gear's.4:10's all the way!!

 

Any idea the price range of a shop install for the gears?

How does it work? 4.10 changes it so it uses less rpms all together? So its more high end power or the other way around.

Still looking for an answer if I could install the plenum and pulleys by myself.


Thanks guys!

 

Without the throttle body the Plenum is'nt going to help much.And yes you could do both of those.

 

https://mustangboards.com/general-te...ar-thread.html

 

I decided to go with 3.73 gears, 4.10 was a bit over doing it.


I think I'm going to buy the catback then get that pulley installed.

You guys still not that sure if plenum will do much by itself?

 

4.10's
Plenum with throttle body. Not by itself.

 

When you say with throttle body do you mean I would have to replace that too to see any results? :P

 

Doing the throttle body and plenum together gives you the best benefit. You won't see much if your plenum is bigger and the throttle body is stock. Same holds true with having a bigger opening with the throttle body and a stock plenum intake. I made the mistake when I started and did the throttle body first.

Gears are not a "do it yourself" type job for most people. I paid $180 for my gear set (Yukon gears) and about 200 for labor. Took a good 3 hrs to have them done. I had a little extra cost by having them fill the rearend with Royal Purple gear oil. You have been given some good advice and you have to do what is the best choice for you and your vehicle.

 

3.73 = ***** gear 4.10 + = Man gear! So go steep or go home!

 

I can agree with that. I thought 4.10s would be way too much gear. WRONG. I have an auto and it now just about feels like I thought it should have when I bought it new.

 

Do NOT do 3.73's!! 4.10's PERIOD!!

Do a search on every Mustang forum and you will see others that preach the same. DFTG!!

 

4.10s it is. lol

 

what kinda gas mileage do you get around town and on the highway at 75 with 3.73's vs. 4.10s i dont take my car to the drag stip cause we dont have one but i like to mess around town and have a quick car but i still want to be able to get the 140+ quick

 

20-23,24 ish

 

so if i got 4.10s i can still get 23 mpg on the highway at 70-80? if i can get that then id do it cause i dont do allot of highway but i got on a trip once in a while for a few hours

 

It really depends on your driving style. I drive very conservatively so my mileage reflects that. If you are constantly on the gas around town, you can expect around 20 or so with the 4.10's. I got 28 MPH with my car when it was new on my trip from Baltimore MD to Williamston, NC.

 

That was w/ 4.10s!? I can only manage 30 mpg if I'm doing all highway at 80 mph w/ no traffic and the stock 3.27 gears. And I was able to do that only once.

 

No, 3.27's

 

Ok, that makes sense.

 

on the ride back with my car on the highway driving pretty conservitively i got prob 25-27 mpg. Id like to do 4.10s if you can still do a 20 hour trip if you wanted to, and get around 23mpg still