[MAXRPM]

Is there any difference in HP between a 2.25" compared to a 2.5" DP . I currently have RC2/3,,PP520, and 2.25" straight pipes, I am debating whether or not I should change it to a 2.5", I would have to see that there is gain in order for me to make the change thanks for your replies..

 

[chittychittybangbang]

Maybe.

With such a small increase in size, what's important is a smooth radius and transition.

As long the pipe doesn't increase the amount of turbulence or resistance, then yes it will have an increase. Will you see/feel it? Probably not.

 

[iansw]

Depends on how much your wallet sees it!

You won't feel it as much as the rocket chip or a bigger combo. I would think that if there's excess backpressure in the exhaust and the DP helps, then it is worth it. Since you already have a straight pipe, I don't think it will be worth it as much. I would think that the turbo exhaust housing would be a bottleneck.

 

[chittychittybangbang]

The turbo exhaust housing is a bottleneck but not much of a bottleneck.

I think it should help but the DP that I have seen out there aren't really superb. T hey are decent but the one part I don't like is the expansion section. It's a litte steep, a more gradual transition would flow much better but it would also cause much higher fabrication costs. Overall, there should be a slight power increase.

The rule is that the less backpressure, the greater the differential, and the more power the turbo can make, everything else being equal.

 

[fstjetta]

I think 2.25 is already bigger than stock.

These turbos don't flow too much but every little reduction in backpressue helps. I would think first remove the cat, get a better downpipe, and you should be all set. A flow-through muffler really doesn't reduce flow very much, just avoid louvered mufflers and try to get perforated mufflers and a muffler will help reduce buzzing.