stanglvr

i am planning on buying a cat back system for my 2001 v6 mustang. I am interested on the steeda cat back system for $599. Is it true that it will add 20 horsepower. Will it decrease my torque if i only have a mac cold air intake and underdrive pulleys? And how big are the pipes and the the tips. And is this worth doing for over 600 dollars or should i just make another modification to my car. I would really appreciate your help guys. thanks

csledd

20 hp is probably not accurate.. I honestly don't know how much it would add to a v6 but I'm going to guess that the tips are 3" or 3.5". I have the Steeda cat-back for my GT and my tips are 3.5". Steeda is always more expensive and I like the quality of their parts, but their exhaust is actually Borla, which is another good brand. I'm going to copy and paste this article from mustangexhaust.com over.. I would definately read it because it explain dual exhaust on v6's fairly well...

The biggest hurdle to making any V6 sound like a V8 is the simple fact that you are missing two cylinders, The same way a V8 sounds different from a V10. If you have ever stood next to a Viper and wondered why it sounded "funny," it's because of the additional cylinders.

You can change the tone of your exhaust with different muffler designs (baffles, perforations, absorbing materials, and so on) and also use different pipe diameters, but you're never going to get the same V8 sound as a 5.0 or 4.6 with a throaty cat-back on it.

For the typical V6 Application, using dual exhaust and larger pipe diameters can actually hurt low-end performance to some extent. Engines need backpressure in the exhaust system to help scavenge the cylinders, and too large of an exhaust system will hurt this process. Most of the V6 dual kits out now are only splitting the single exhaust into two outlets, so there should be minimal effect, if any. I would say that most V6 exhaust sales are to people who want the V8/GT look and a nicer exhaust note, but who aren't terribly interested if the system makes more power or not.


Below is why too large of a pipe diameter can hurt you.

A restrictive exhaust creates back pressure in the exhaust system that hurts your vehicle's performance in two ways:

1. The engine has to work harder to force exhaust gases out of the cylinders.
2. Engines cannot scavenge burned exhaust gases out of the cylinder efficiently. This leaves exhaust gases in the cylinder to dilute incoming air/fuel mixtures and rob your engine of horsepower.

Pipe Diameter:

A common misconception is that the larger the diameter, the better the system. But, bigger isn't always better. Systems that are too large in diameter can actually hurt low-end performance.

As a general rule, switching to a performance system that is 1/4" to 1/2" larger than stock will provide you with the best horsepower increases. To determine which pipe diameters will be best for your system, decide what RPM range your engine will operate at, most of the time. Smaller diameter pipers will produce low to mid RPM torque. Larger diameters produce mid to high RPM torque.

But keep in mind that if you increase the pipe diameter TOO large, then you have a much larger area the exiting exhaust must cover. If the engine pushes out "X" amount of exhaust, and the exhaust is too large and the exhaust exiting the engine cannot fill the pipe, it cools quickly, slows down, and causes a restriction also. The hotter you can keep the exhaust, the faster and easier it flows. This is one of the reasons why an off-road pipe loses some low-end but gains more top-end, which I hope you will understand with the example I use below.

If you want an example, take a straw and put a kink in it and blow thru it softly. Notice how some of the "exhaust" goes out but most stays in your mouth (engine). Now try blowing through it as hard as you can, simulating WOT and high rpms on a stock exhaust, notice how your are almost choking on your "exhaust" now, simulating poor flow at the benefit of more low-end torque.

Now, take a decent sized diameter straw (Mcdonald's straws work the best) and blow through it slowly. Notice how all air is going out the straw, and none is staying in your mouth (no backpressure, poor low-end torque). Now try again, but blow through it as hard as you can. Notice how all the air exits as fast as you can blow it, simulating a high flow exhaust, maybe TOO much.

The trick is to find the balance between the two. High-end flow, while saving low-end torque. Granted, I don't expect you to have a straw hanging out of your mouth while you are choosing an exhaust size, so I made the chart below for you to follow, I just wanted to give the reader an idea on what happens when they change their exhaust pipe diameter using the straw scenario.

Here is the chart mentioned above, it seems tried and true as far as what you should go with to keep that low-end grunt and top end scream we all love!

__________________

CAP
DSG Registry
2003 Mustang GT - daily driven
check out my cardomain for more info
296 rwhp / 310 rwtq

Money spent @ AM: $4623.20

1984 Mustang Hatch - low budget project

stanglvr

thanks for your help, anyone else with their opinion? i want to know how big are the actual pipes