2007GT/CS

What can I expect in terms of a performance improvement? 1 5/8" vs 1 3/4"? Off road vs. catted x-pipe.

Retune required?

Thanks!

22kart22

Retune required. It will run lean.

I'd expect to see atleast 20 hp with a supercharged application

06Saleen3V

I know ARH suggests 1 3/4" for FI applications but apparently it is better for some reason to run 1 5/8"...Dont ask me why, that is just what I have heard

2k6silvergt

I would agree that you should at least be able to pick up 20 extra hp at the wheels. I called around a few places before I got mine and most said either would work on a boosted application at lower boost levels, but if I planned on doing a lot more mods (heads, cams, stroker motor, etc) or running high boost that I would want to got with the 1 3/4. Midpipe is up to you, people choose different ones for a number of different reasons. And a retune is definately required especially to get the most out of the headers.

Mustang3GT07

What about a non supercharged car? how much hp gain from longtubes?

mygt500

You will breathe better with the 1 3/4 LT with any FI. You want to get the exhaust gases out as fast as you can therefore reducing heat and increasing HP. I read about 10-15 RWHP with LT headers and they are a pain to install. (or if you have the right equipment- labor intensive). A retune is a must and the off road setup will be loud and unrefined IMO and from what I have read is not worth it. High flow Cats and a x-pipe will breathe better than an H-pipe. It is personal preference IMO on any exhaust work. Here is an article for mid length headers 1 3/4 inch for some examples....good reading! Enjoy- Hope it helps http://www.alternativeauto.com/water...texhaustupdate

22kart22

With an non-supercharged car you are looking at like 1/2 of that....If that

sevenleaf

I'm running Saleen SC with Kooks LT and offroad Xpipe to Bassani Mufflers, I love it. If you call up brenspeed and ask them if you need a retune they will say no unless you need the O2 shut off. I dyno'd my car 429 RWHP a week before install and I hit 443 with bad gapped spark plugs and messed up boost after installation. So I got over 15 RWHP easy from the exhaust. I'm trying to get into dyno before Cobra Day here but the shops are all busy. 3 days ago I fixed my boost and installed new gapped spark plugs to .030 and installedMSD coil on plugs lastnight. Install of the headers and xpipe took about 4 hours

drbobvs

Retune is usually NOT required. It's all in the tune. JDM has told me my tune is fine with or without headers, Brenspeed has said the same thing.