Does anyone know the power benifits of upgrading to a 3in downpipe? I am considering getting a new downpipe fab'd up since I will be turning the boost up. Some where around 20psi as long as my turbo is efficient in that area. I will also be using either meth or e85 for fuel by the way.

I know we have many tuners here that could maybe chime in, even with other then s2000 results.

Thanks
Martin

 

From all that i've read, back pressure is never a good thing for your turbo. So going 2.5 to 3in is going to only add power. If you look at the Mitsu guys, that's usually one of the first upgrades even on a stock turbo.

 

i went from a 2.5 to 3inch dp and gained a bunch of power. The spool of the turbo is much better with the larger DP. Interestingly enough, i recently went back to stock exhaust with ECO and my spool has stayed exactly the same with the 3inch DP and stock exhaust compared to my 3inch single from before. This is in stark comparison to my older log manifold and 2.5 DP, that took much longer to spool.

 

Yeah I am currently making boost before 3k. I start seeing boost around 2700-2800rpm with a t3/t4 .60 a/r. Just want to make sure it is worth the money.

 

You will gain a little, but not much on a small turbo. You will see more results with a bigger turbo, but its almost always worth upgrading.

 

there's a lot of variables, I think it really depends on the power you're pushing. 350whp maybe there's no difference, 500whp and maybe you notice a big difference. talking with Mase a little about it and he was saying up until 500-600+ whp the differences were fairly small between the two sizes.

again every setup is different, if the downpipe is short and fairly straight with few bends it probably won't matter that much. lots of turns and longer and it may make a big difference.

 

we were tuning a prelude and the customer wanted a 3" dp made instead of the 2.5" one that was on the car. after the swap the car made 399whp and boost levels were achieved earlier in the rpm band. it gained roughly 40whp over the 2.5" with the same tune

 

^Thats some serious improvement for a piece of pipe. Sounds like 3" is the way to go.

 

Im upgrading from 2.75" dp to a 3" dp with a cut out also before the muffler. The bigger dp definately makes noticeble gains with my t67 .70 a/r. With my 50 trim set-up 2.5" dp with a cut out i lost a little bit of torque.

 

I would NEVER run anything less than a 3" on a turbo setup, regardless of turbo size.