i'm debating if i should go 2.5" or 3"... i hear 3" is pretty big and i might have ground clearance problems.... also i'm just running 10 lbs when im done so, what do u guys suggest?

 

3''

 

Definitely 3" Backpressure is THE DEVIL!!!

 

3"

 

You can get away with 2.5" If it's going to be a pain to make a 3" fit, just go 2.5" Yes of course you'll make more hp with a 3" but its not like anything under 3" is horrible.

 

Is back pressure a issue with bosted cars?

 

More backpressure= more likely to boost spike. Of course, the less boost the better if you have a 2.5" or smaller DP and exhaust. For 10psi, I would not go as small as 2.5".

 

3" for turbo

 

I thought it was the other way around (?)....That's why some Drag owners notice spiking when they upgrade to 3"....the exhaust doesn't want to go through the wastegate, it wants to go through the manifold and out the exhaust piping.

 

This is what I understood from other people's examples.

 

I'm just now getting ready to go to 3". I was using 2.5" last year.

 

That may be with the Deltagate.

 

Considering the enormous increase I felt going to a test pipe from a stock cat this week, I can say for sure that backpressure makes a BIG difference on a turbo car.

 

That's wrong 97CivicFerio. With any wastegate, if you run a higher flowing exhaust (open exhaust or large piping) you will boost creep.

 

Ok, so you're saying if you don't want creep we better run what? A stock exhaust? 2"? 2.25"? That does not make any sense to me because a 3" exhaust on a turbo Honda is a MUST to make the best HP. Now is part of that HP increase due to the spiking? This cannot always be the case.

 

LOL. Ok.. listen. Going to 3" is going to cause creep in a *few* cases. But you can control creep by using larger vac lines, having a better designed WG and Manifold, etc. Going 3" doesn't mean you'll creep forever. It's all in design. If you run a really restrictive exhaust, like stock.. then you wont reach full boost, or it'll take longer to do so. No poo poo that the larger exhaust produces more HP. I never disagreed with that. I'm just letting you know how things work.. basically a larger exhaust CAN induce creep.. while a restrictive exhaust limits spool-up and full boost.

 

Ok, it just sounded like you meant that by going to a 3" you would creep no matter what. Sorry for the confusion.