Tailpipes 2.5” vs 3”

[XLexusTech]

500 hp naturally aspirated ls3 I am going with 3” to the muffler starting to wonder if I am going to be able to get the 3” over the rear suspension...so I am considering 2.5”

what would the performance impact be ?

[1985olds]

Hopefully this answers you question.

https://m.youtube.com/watch?list=PLGvTvFzdMg_O2T3UdUEt5dIHutSOu7srE&v=_PVXvHkr-Vs

[68Formula]

Coming out of the mufflers, the smaller pipes won't make a lick of difference except maybe knock a decibel or two off.

[XLexusTech]

Hopefully this answers you question.

https://m.youtube.com/watch?list=PLGvTvFzdMg_O2T3UdUEt5dIHutSOu7srE&v=_PVXvHkr-Vs
Kinda but not really they conclude that through the muffler 2.5 to 3” third is a notacable difference .. but I am asking a lot after the muffler only and they are at 600+ hp with a larger cid (more air) engine so too many significant differences to draw any conclusions

Thank you for the link it definitely helped

[csouth]

You could also step down after the muffler and run 2.5" tailpipes. The exhaust will have cooled by then making the gasses more dense requiring less space.

[XLexusTech]

You could also step down after the muffler and run 2.5" tailpipes. The exhaust will have cooled by then making the gasses more dense requiring less space.

yes thats what i was asking. would that step down have a large performance impact @ the 500 HP level..

[andrewb70]

yes thats what i was asking. would that step down have a large performance impact @ the 500 HP level..

I'd say no difference.

Andrew

[68Formula]

I'd say no difference.

Andrew

Yup, no difference.

[MAGONSTERZ68]

Yup, no difference.

agreed no difference other than sound, dynoed car with full 3" over the rear end, 467 to the rear wheels.
later modified with a set of spintech traverse mounted, 3" in and 2.5 out for the sake of dropping a decibel or two, hence the second set of cans.....and re-dynoed at 461 to the rear.

[65 drop top]

Should be no noticeable difference with the 2.5” after the mufflers. Even 2.5” from the headers back wouldn’t hurt much either, if at all. 500 hp is about the point when you would consider 3”.

[CarlC]

Flowmaster makes a very nice long-transition 3" ==> 2-1/2" coupler. 3" to before the mufflers, the transition, 2-1/2" in/out mufflers, then 2-1/2" tailpipes. I had this setup on the Camaro for years with good results and quite reasonable noise levels with Magnaflow 17" case length mufflers.

There used to be a Dynomax catalog that listed horsepower ratings for mufflers. If memory serves a single 2-1/2" muffler was rated for well over 600hp.