dtr_dave

I no genius but I do my research before making large purchases.

When I purchased my twins I was concerned about the manifolds they came with because I used to own a 2002 dodge and I purchased a manifold from ATS. After installing it, it felt slower. Finally I went and had it dynoed I was down 25 hp. I put the stock manifold back on and was back up on power. I left the stock manifold on.

Fast forward to buying my twins I really questioned both BD and DPS about their manifolds. Both places assured me I wouldn't lose hp with theirs. DPS explained that the turbo was the bottleneck not the manifold, and the reason I lost hp with the ATS was the tube sizes are larger than stock and therefored slowed the exhaust velocity causing the turbo to spin slower.

I sat and argued this with them on the phone. Finally to shut me up they emailed me a quote from a turbo design book, in reference to exhaust manifolds, here it is "RULE: When a choice exists as to tube size, always opt for the smaller, to keep gas velocities high." Maximum Boost Desiging, Testing and Installing turbocharger Systems by Corcky Bell pg. 120.

I believe both the BD and DPS use smaller tubing than ATS. So not only by the book but by my own results I've seen the truth to what they said.

Snapoff

Yup, like I said John Todd is an engineer....He doesn't guess about that sort of thing.