3in or 2.5in exhaust on V6, Help In Choice

[TTUCK06GT]

Hey guys can you help me out im alittle confused lol. I know that the Injen exhaust is 3in but i was always told that 3in was for forced induction only, thats its over kill on NA motors!

So my question is whats better for our V6 motors the 3in or 2.5in?

I have a Fujita CAI, OBX Longtubes with 28in magnaflow restonator 2.5inlet/2.5outlet and sock piping to the axle where i put a dump after the axle. I have a 3in catback in garage but had to custom exhaust after header install. So im trying to figure out to hack and weld my 3in exhaust back on with an expansion pipe or just finish the rest with 2.5in.

[phast007]

My 06 v6 came with a beautiful two peice when I bought it I'm sure its HKS, but also sure its. 2.5. Sound is amazing and quiet in 6th gear. I'm not too sure but cant it even hurt the performance if you go too big??????? idk

phast

[HAHA NO]

I'm 3inch from headers back. Car runs and sounds nasty...no complaints here.

[Karnak]

Originally Posted by HAHA NO

I'm 3inch from headers back. Car runs and sounds nasty...no complaints here.

Dual or single all the way back haha?

[HAHA NO]

Originally Posted by Karnak

Dual or single all the way back haha?

My injen only came in a single

[MFTK]

Mines 3 to the axle then 2.5. To each muffler

[tiger blood]

Parts Directory > Engine Parts > Injen SES Stainless Steel Full Exhaust System.


- check that thread out. Should help a little

[TwilsonD7]

Originally Posted by MFTK

Mines 3 to the axle then 2.5. To each muffler

Yeah don't bottle neck your exhaust like this guy, 3" is overkill and personally sounds like shit, If you go 3" put a 3" muffler on. Headers stock center pipe and a bolt on muffler is the best sound I think and you don't loose the low end power with the no back pressure of the 3"

[Gravey]

Originally Posted by TwilsonD7

Yeah don't bottle neck your exhaust like this guy, 3" is overkill and personally sounds like shit, If you go 3" put a 3" muffler on. Headers stock center pipe and a bolt on muffler is the best sound I think and you don't loose the low end power with the no back pressure of the 3"

going from a 3 inch pipe to two 2.5 inch pipes will actually flow better then a single 3 inch pipe. its simple math

[HAHA NO]

Originally Posted by Gravey

going from a 3 inch pipe to two 2.5 inch pipes will actually flow better then a single 3 inch pipe. its simple math

I'm going to have to disagree with that...but to each their own. All I know I'd that my exhaust I still have back pressure enough that when I give her I shoot out a nice blue flame so it works for me and I run nice times with this setup.

[Gravey]

just do the math and look at the numbers. the forumla is pi*r^(2)

[MFTK]

i have no back pressure at all

[phast007]

dude my HKS came in a pefect one peice to the bolt muffler, and 2.5. Like I said perfect sound no loss of power.

[HOMESLICE]

Originally Posted by HAHA NO

I'm 3inch from headers back. Car runs and sounds nasty...no complaints here.

would you say your car runs a 275-285 whp with intake headers and the injen 3" exhaust from headers back? or would the 2.5 be just as efficient as long as you have intake and headers. i feel if you have headers then it would be a good idea for the 3.0" exhaust. We still need more tests on 3" exhaust comparing factory, mild builds (intake w/ 2.5" vs 3.0" exhaust). any dyno results with just the big three? and did you get a bigger/better y pipe?

[joeyb]

since you don't have the twin exhaust, I'd just do the 2.5" but I doubt the 3" would lose you anything you'd notice - if anything at all. I had the 3" on my bolt on for a very long time and it was just awesome. as Matt is saying, that's what he runs now and it's great. so I don't think you could go wrong, either way. just down to preference and what you are wanting to spend. I will say I don't see how any system could sound better then the Injen 3", tho. just my opinion.

[HAHA NO]

Originally Posted by joeyb

since you don't have the twin exhaust, I'd just do the 2.5" but I doubt the 3" would lose you anything you'd notice - if anything at all. I had the 3" on my bolt on for a very long time and it was just awesome. as Matt is saying, that's what he runs now and it's great. so I don't think you could go wrong, either way. just down to preference and what you are wanting to spend. I will say I don't see how any system could sound better then the Injen 3", tho. just my opinion.

thank you...it all comes down to want you want.

[HAHA NO]

Originally Posted by HOMESLICE

would you say your car runs a 275-285 whp with intake headers and the injen 3" exhaust from headers back? or would the 2.5 be just as efficient as long as you have intake and headers. i feel if you have headers then it would be a good idea for the 3.0" exhaust. We still need more tests on 3" exhaust comparing factory, mild builds (intake w/ 2.5" vs 3.0" exhaust). any dyno results with just the big three? and did you get a bigger/better y pipe?

yes i have a 3inch custom y pipe

[Elemenohpee]

I have a 2.5 turbo elbow to a 3' cat back downpipe... no muffler rite now. You all can call me crazy but my car sounds like a fucking Diesel, ive been told this too many times to count lmao. I think im gonna make a video with my exhaust now lol.

edit: sorry forgot to answer the question! i dont feel like getting into an argument with anyone but thier is a thread in the F/I section about exhaust size on N/A and F/I cars and the thread is a copy and paste from someone talking directly from Garrett Turbo co im pretty sure. Anything above 2.5 is kinda overkill if your not f/i and he explain why in the thread if you wanna check it out.


here is the thread.. this should debunk any arguments

Turbo exhaust theory

[HAHA NO]

As a good firend put it on here....

Originally Posted by da9gsr

you need exhaust velocity, not backpressure, backpressure will not allow your motor to expel the gases effectively, and thus make your motor run like a bag, velocity will cause a scavenging effect and expel gases faster, the best exhaust is one that has zero backpressure at the maximum power range of the motor

Im not on here preaching the 3 inch...if its not want you want then get a 2.5. What I hate most in life in when people bad mouth a setup that they do not have. Is it overkill Probably, buts thats the exhaust i choose and im working around with. I run 13's all day, I run a higher whp and Tq then most people with a the same mods and a 2.5 exhaust. My setup works for me and has given me the numbers im looking for. Its deosnt mean there is a car with in here with a lower exhaust diameter that isn't running a higher hp or tq then me. Every car is different on here and mine works for me. Im just giving my 2 cents on the 3 inch, not here bashing a 2.5 exhaust. The guy asked abouth both so....

[Elemenohpee]

^ for the record man im not raggn on you or anyone else with 3' n/a to each his own. Im just trying to answer the OP question as best as possible in my own words.

[HAHA NO]

Originally Posted by Elemenohpee

^ for the record man im not raggn on you or anyone else with 3' n/a to each his own. Im just trying to answer the OP question as best as possible in my own words.

dont worry its not you or anyone just a general statement. Its all good not mad at all just saying.

[Elemenohpee]

Word, it's hard to read people sometimes.. Especially on a forum.

[HAHA NO]

Originally Posted by Elemenohpee

Word, it's hard to read people sometimes.. Especially on a forum.

yeah no shit..im an asshole so i can be harsh at times but i try to play nice.

[HOMESLICE]

If i am going nitrous down the road, would you recommend me going 3" exhaust all the way through to the headers with a bigger y pipe?

[Ricoswave]

2.5" is retarded loud with headers. I can only imagine 3".

[HAHA NO]

Yeah I have many vids on here with the setup now while I was a dyno.

[ptr149]

Ya I have 3" from headerback with stock manifolds and it sounds great and improved my quarter mile time compared to the stock piping