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[imburne]

For a b18c1, hx35, 64mm throttle body, 2.5 inch exhaust.

Go with the bigger or smaller piping?

[92CXyD]

Keep all 3", more surface area for advertising, and potential bling when ya pop the hood.  ;D

Depends on your HP goals.

600+bhp then yeah 3"

[ratcityrex]

2.5 will be fine, but I did 2.5 from turbo to ic, and 3 from ic to my baller pbt throttle body.

[bigdaddyvtec]

Under 700 no NEED for 3.

[imburne]

Thanks for the info everyone. Got the 2.5 and collecting more parts.. About $500-$700 left on the build for completion.

[PhilStubbs]

I talked to JD about the same thing a little while back. I went with 3" cause the cost was basically the same and spool time seems the same too. It looks badass(meh) but I now have pipes for as much power as I could ever imagine pushing through a Honda with no downsides.

[92CXyD]

I talked to JD about the same thing a little while back. I went with 3" cause the cost was basically the same and spool time seems the same too. It looks badass(meh) but I now have pipes for as much power as I could ever imagine pushing through a Honda with no downsides.

I saw no difference in pressures when using 2 and 2.5" (older) IC and 3" (newest) IC piping on my SC14 on my D16z6/y8/vitara/eagle build. 

[Tim]

2.5 will be fine, but I did 2.5 from turbo to ic, and 3 from ic to my baller pbt throttle body.

newb questions, why do people put smaller diameter from turbo to ic, and larger from ic to throttle body?
I see this a lot.

[malichite]

Dont be a pussy, just run 4" already and get it done!  That or the biggest PVC you can find at lowes and use the savings to buy beer.

[92CXyD]

2.5 will be fine, but I did 2.5 from turbo to ic, and 3 from ic to my baller pbt throttle body.

newb questions, why do people put smaller diameter from turbo to ic, and larger from ic to throttle body?
I see this a lot.

Probably because they are using a 70mm or larger tb. 

[PhilStubbs]

2.5 will be fine, but I did 2.5 from turbo to ic, and 3 from ic to my baller pbt throttle body.

newb questions, why do people put smaller diameter from turbo to ic, and larger from ic to throttle body?
I see this a lot.

Probably because they are using a 70mm or larger tb. 

i never really understood that either. kinda seems opposite of what you would want. hot air coming out of the turbo would be less dense then after the intercooler it would be more dense and need less volume. i could be way off, but it my head it makes sense

[Tim]

2.5 will be fine, but I did 2.5 from turbo to ic, and 3 from ic to my baller pbt throttle body.

newb questions, why do people put smaller diameter from turbo to ic, and larger from ic to throttle body?
I see this a lot.

Probably because they are using a 70mm or larger tb. 

i never really understood that either. kinda seems opposite of what you would want. hot air coming out of the turbo would be less dense then after the intercooler it would be more dense and need less volume. i could be way off, but it my head it makes sense

That is exactly how my thoughts were, but I never asked anyone that would actually know.

[92CXyD]

2.5 will be fine, but I did 2.5 from turbo to ic, and 3 from ic to my baller pbt throttle body.

newb questions, why do people put smaller diameter from turbo to ic, and larger from ic to throttle body?
I see this a lot.

Probably because they are using a 70mm or larger tb. 

i never really understood that either. kinda seems opposite of what you would want. hot air coming out of the turbo would be less dense then after the intercooler it would be more dense and need less volume. i could be way off, but it my head it makes sense

That is exactly how my thoughts were, but I never asked anyone that would actually know.

My original reason for using 3" pipe was to have less flow loss due to bends.

But it actually made it easier route my piping in respect to my setup.