2.5 VS 3" Exhaust tq/hp what will it be ?

[T5superduty]

What would it really come down too if say with my combo I made the 358 lb-ft torque at 4100 rpms (flywheel) like in the article you all have seen before. That was done with full 3" exhaust with flowmasters. If I went to 2.5 " What kind of real world torque numbers would be increased ? I would only think mabye 10 at the most and it would be made at lower rpms, what do you all think ?

[Dark_5.0]

I have a 2 1/2 inch H-pipe with 3 inch tail pipes cause I seen the same set-up in a mag and it made the most power.

I think full 3 inch exhaust would hurt your torque substantially and only net a moddest gain in HP.

I say 2 1/2.

[T5superduty]

yes that is what I was asking. In the test done below "which is what exactly what i have in my car" it made 358 torque with 3" exhaust. I'm asking how much power I would be increasing it by if I gave it 2.5 instead ???

[Dark_5.0]

Its hard to say, but on your engine full 3 inch exhaust would make your car slower.

To put things in perspective. My brother has a 420HP 327 in his 81 camaro auto, he had 2 1/2 exhaust and decided to try 3 inch. His 60ft got a tenth worse and the 1/4 got 2 tenths worse.

The only positive thing that came from it was he picked up .8 mph.

[T5superduty]

I dont think some of you understand what I am saying. I am just asking how much torque will I really get if I switch to 2.5. That motor makes 358 lb-ft torque with 3" exhaust. How much would it make with 2.5 ??????

[Ackbar00]

My old system was MAC longtubes with 3In H-pipe and mufflers. It made 324 Ft trq at the wheels. No torque hurt here

[T5superduty]

Hmm ya that seems about right... how much torque do 5.0s usually get stock at the wheels? 324 is not too bad. According to that dyno sheet I would be making around 305 + torque at the wheels. Since it made 358 flywheel. What you think ?

[jonnyk]

I doubt 3" would hurt you but fitting 3" over the axle is just about impossible. I would stick with 2.5"...it will easily handle up to around 500 horsepower with no losses, and stronger bottom end power too (can't really put a number on it...every combo is different).

[420nitro]

I agree with Jonnyk. Its almost impossible to tell you. If some one gave you a number he would only be kinding himself and you. We all agree that you will make more torque with a 2.5 inch exhust over 3.0 inch. for a street car seeing drive duty. I won't even consider putting on a 3 inch exhust untill I know the power plant is making over 450 flywheel horsepower with all of its power adders if any.

[429mustang]

Whats the deal with the Dr. Gas X-pipe (for longtubes) that goes from 3'' to 2 1/2'', is there a noticable sound/power difference than the regular 2 1/2'' x-pipe? It cost a bunch more, is it worth it?