All of the piping and bends I bought for this are 1.5" with the exception of the flex section, which is 1.75". I was planning to flare out to 1.75" and use 1.75" piping where it merges into the downpipe. Well, I finally found someone who sells 1.5" flex sections, so I can now use all 1.5" piping if I want. Some of the closed loop dumptube pics I've seen flare out to a larger diameter piping before merging with the downpipe. My question is if it makes any difference as far as being less prone to boost creep, or even turbulence, if I use 1.75" vs 1.5" piping at the end. Is one better than the other?

 

Anyone?

 

Bueller?

 

I have no proof to back this up so take it FWIW...

I don't think the size of the piping matters, but more the angle that the dumped exhaust is introduced into the exahust flow. You want to get it to all flow as close to the same direction as possible. When it is introduced at a more severe angle...thats when it causes turbulance and interupts flow...

 

Thanks, man. I read about this, too. Anyone else?