The main reason you dont see alot of dual exhausts on Diesels is they only have one exhaust manifold, not 2 like a V6 or V8. In those applications, they really benifit from dual exhausts since a dual 3" exhaust for example will flow very well. 2 Seperate systems for each bank of cylinders. In our application, a dual 3" exhaust being fed by one 3" turbo outlet is a little overkill. Just like there is no real gain in a single 5" exhaust, a dual 3" exhaust would be like having a 6" exhaust, so once again, there is no gain.