Contour Enthusiasts Group Archives Forums General Dyno and Drag Dynos comparing 2.25" exhaust to 2.5" exhaust?

Does anyone have dyno graphs from a 2.5L or a 3.0L Duratec comparing a 2.25" exhaust system to a 2.5" exhaust system? I know I have seen dyno graphs that show gains by switching to a 2.5" system, especially if you have headers installed, but I cant seem to locate any of the graphs.

Nikolas

That's a rather broad request. Do you mean ANY system with 2.25" and ANY system with 2.5"? Assuming different mufflers are used and different placements, different gains will be had. Try brullen, they usually have graphs for their stuff. Wouldn't buy from them though...are you considering making a system for us perhaps?....

Bassani=2.25"
Bosal=2.25"
Borla=2.25" to 2.5" in the rear (I heard)
Brullen=2.25 or 2.5in, I can't remember and I don't even know if they're made anymore.

Yo-Dude=2.5 or 3"
Stock SVT=2.25"

I'd be interesting in a comparo of ANY of those. So far I've only seen the bassani vs. borla, which was erratic at best.

Wow, those are all really 2.25"?? How do they get the gains out of them that they do by just making a system with different mufflers?....The stock SVT system is mandrel bent, so no real gains to be had there...replace the mufflers and res (or no res) and logic says you should be up there in the 6-8 whp gains they get from cat backs....something doesn't add up here...

Now I am beyond confused. I had no idea that these aftermarket systems were also made in the same 2.25" sizes. Which exhaust system will give me the most horsepower? Money is no issue, but I don't want to spend an outrageous amount for a few extra hp. I also don't care how loud it is, as long as it doesn't sound RICE. Should I just modify the stock exhaust? I have been considering new mufflers and no resonator on the stock setup or a trubendz borla system with no resonators. anybody have any good ideas on how to get the most power from the cat back. I will also be getting a y-pipe if that helps any. THANKS!

y pipe = good. I'm a little confused on the rest of the details right now also. Agreement around here is that Trubendz is the best bang for your buck, and they use 2.5". I say go with that and an optimized y.

Brullen is 2.5" and drops down to 2.25 at the rear y split

straight through muffler design

For the 2.5L, 2.25 = 2.5" for most purposes.

I have looked at the 2.25 Bassani gains side by side with 2.5" SCA and Brullen...gains same across the rev-range within 1-2 HP. Average gains above 4K RPM same (about 6 HP) Peak gains same...SCA 6HP, Bassani 7HP, Brullen 10 HP...however, this is misleading because in the pre-Brullen comparo they did not go to redline and it was still gaining power. At the last point on the curve where both plots were present Brullen was at +7 HP.

These were all on a 2.5L SVT with intake mods but not headers. On a 3L or FI, I think 2.5" would be clearly better, MAYBE on a heavily modded 2.5 (but I doubt by much). Agree with Demon that if the stock SVT 2" resonator (the big prob) and mufflers were replaced with Magnaflows it would prob be comprable (as the stock mandrel piping and Y are fine) but I do not think this has been dyno documented.