Hi, i just bought a Greddy kit and was a bit sad to find out the downpipe looks like it was custom made by someone, well anyways, it measure 1.5" :S
Now, i have some 2.5" mandrel bend tubing here and was wondering how big a difference it would make having a 2.5" downpipe rather then the 1.5". Is 1" gonna give me any noticeable power gains? Oh yeah, btw, catback is 2.5" too
thanks in advance honda masters!

 

HECK YES, it'll make a huge difference.

 

any ideas? HP Wise?

 

2.25 to 3 inch gave me 30 hp...

but that was a full turbo back..

 

so i guess im looking at around 15 hp gain???

 

HP gain is hard to tell, but I guarantee your turbo will spool up much, much faster.

We're not just talking another inch of pipe here; it's the area that's important. Going from 1.5" to 2.5" is going from 1.77 in² to 4.9 in²... That's a 277% potential increase in flow!

Even if your wastegate is set at 4 PSI, the difference is that you will make that boost at 2500 RPM instead of 6500 RPM. A major difference.

 

yea, i would suggest you to make a 2.5" downpipe, 1.5" is tiny

 

Spool time will be good for u.. go for it...-0-)

 

^
word. When I first turboed the Rio I had the stock 1.5" exhaust on it still, and I couldn't even spool the little TD05 to 5 PSI.

 

LOL thanks guys, i will use the 2.5 dp then