2.5" or 3" down pipe

[chuckdog_5]

ok, i got a 90 talon tsi awd. the nornal mods like the free ones, big 16, front mount, etc..... well i still havent got my down pipe on, but some peeps have been tellin me that 3" is too big or something, and 2.5" is as big as i should go, is any one out there that has 3" have any probs, let me know what you guys think
lata
charles

 

[echo]

3'' is better. the bigger around the less restriction and the more flow.

 

[chuckdog_5]

thats what i thought, its juss some peeps are sayin 3" allows to much air and that makes sense also

 

[CH152]

More air through is less restriction, your turbo will be happy it should bring out its full potential, even a 2.5 is better than stock as 3 being the best, its up to you, IMO i would go ahead and buy a 3" dp

 

[alIan]

3". It's a turbo car, the less backpressure the better.

 

[CH152]

Originally posted by alIan
3". It's a turbo car, the less backpressure the better.

Simply put

 

[Nappy94]

Go with the 3" DP, you will be happy you did down the line.

 

[chuckdog_5]

well, since the majority is almost always right, i will go with the 3". i should be puttin some good hp after this, i juss hope its enough to smoke those pos z06's( not actually a pos)

 

[HyperGSX]

3" without a doubt.

 

[Wikkedson]

the turbine wheel provides all the pressure needed. So anything after the turbo you want as big as possible. ported o2 housing, downpipe, catback.

 

[gs-twizted]

In your case a 3" would work because you have a 16g and i'd also imagine that you are running more than stock boost. if u run anything less than 17 psi your going to end up overboosting like crazy with a downpipe as big as a 3".

 

[chuckdog_5]

ok, you guys have answered alot of my questions, thanks. ok you say bigger after the turbo the better, well has anyone ever went bigger than 3" and howd it turn out?

 

[Nappy94]

Chance's are you won't need anything bigger then 3". BR now make's 3.5" system's though. A friend of mine run's 4" piping on his 94 Supra TT. He also has 700+WHP, so I don't think it would be necessary.

 

[Fat_Boy]

i have a question stating the 3 inch exaust anyone every have any bottom out probs with that fat of a pipe?

 

[Vinnie]

The only problem with the 3" downpipe is if you don't have a ported to hell 02 housing you will get boost creep, that's why most people go with the 2.5" downpipe, they don't have to worry about boost creep.

I have a 3" catback, never had a problem with it going over stuff, my car is lowered 2" on front and 1.7 on the back.

 

[Wikkedson]

if you have the small flapper on your big 16g then you will most likely get boost creep with any downpipe. I had creep with my small apexi N1 downpipe until i got a ported and dumped o2 and a bigger flapper. Now it is steady.

 

[ghettodsm]

just port the flapper and everthing else out huge and also get a 3" o2 elimantor downpipe from someone like extremeturbo.com or some other company it will be well worth it trust me. no boost creep and it holds rock steady!!!!

 

[BryanK]

You could consider RRE's downpipe... best of both worlds if you asked me. 2.5" from the turbo to the flex pipe, and then 3" from the flex section on. The gases are hotter and have more velocity straight from the turbo, so unless you're running a huge turbine blade, which a 16G isn't, you won't outflow the 2.5" and you shouldn't have to worry too much about boost creep. Thats the downpipe I'm going with.
Bryan

 

[Kevin Jewer]

I also went with the RRE downpipe, very high quality IMO. I built my own mandrel 3" cat back (bushur style) for ~140 bucks as well. Nice gains over the pressbent 2.5 BR turboback I replaced with it. About 1.5 lb/min at my current state of mods, or about 15 hp, at 22-23 psi. I like it.

As for the creep, I couldnt get my 14b below 22 psi on that pressbent 2.5" turboback. That seems to be an extreme case of boost creep, but just to show that it can happen with any exhaust. Porting of the O2 did nothing, the hole size did very little. The bulk of the creep reduction came from porting the wastegate exit area, per the vfaq. Have fun