dbvettez06

Wondering just how restrictive the exhaust system is...They do sound good, how much HP can be gained by just good headers, and by headers and aftermarket exhaust?

bl1nk

From a total exhaust redo about 35 hp, possibly more with a retune

20-30 from longtube headers

5-10 from an x pipe

and the axle backs of your choice for sound

of course those numbers are ideal and will vary

CrazyAl

The stock system is not very restrictive at all. It comes from the factory with true dual exhaust, H-pipe, and 2.5" tubes all the way back.

Cat-back or axle-back (muffler) swaps will get you no HP gain.

Shorty headers are worth 3-5 HP.

Long Tube headers are worth 20-30 HP.

classj

+1

dbvettez06

Wow ...Sounds like a quality set of headers, along with a good CAI/tune will be on my list...If 35-40Hp can be gained, it is a no brainer....

Timmay!!!

Yeah this is proly one of the best factory exhaust systems I've ever seen plus everything can be replaced in your driveway. No welding, all clamps and bolts. Only thing I've noticed is a crimp in the exhaust tubing just fwd of the right muffler. Maybe axle clearance issues?

drbobvs

You know, I might catch some slack for this but I call B.S. I have yet to see any dyno results of a 20+ hp gain buy just changing any ONE piece of our exhaust system. First of all you can't just change to LTs without moving the cats or eliminating them which is likely worth 5-10 hp right there. In fact, if I remember right MM&FF did that 3 month exhaust comparo last yr where they did a full exhaust swap and only saw a grand total of 14 hp. PLEASE, someone post pre and post dyno numbers to prove me wrong! B/C if they do I would be interested in getting a header setup myself as long as it incudes cats.

Skrappy

drbobvs, I have to say I agree with you. I have read way too many posts about our exahust system and everyone seems to agree that there really isn't that much HP in it until you get into some serious mods, SC, tune, etc. The stock system is just very good. There is no real reason to start by spending your money there unless you just want a loud exhaust. Everything back there is mandrel bent and has plenty of diameter and the H-pipe. If you just look under the car, you can see that it is pretty hard to beat two 2&1/2" pipes coming straight back.

Skrappy

WildRed

+1

i went to pypes web site and looked at there dyno results. a pontiac had a 20 something hp gain running OPEN headers. it had a high flow cam they (pypes said gains on a stock motor would be less). if you are stuffing more air in ie s/c or cai with the tune you would see a increase, but stock youd be lucky to see 15. its all about the total package.

67WONAB

Here's my 2006 Mustang GT with MAC Axle-Back Mufflers. The rest of the car is stock. They sound great in person but this clip will give you an idea of the sound.

http://media.putfile.com/2006-Mustang-GT-MAC-Exhaust