I have a set of manifolds off of a 2000 ram 5.9. The opening is 2in. The motor is a stock 2000 5.9 other then a carb conversion..... Reading on this site, dual 2.5 in. exhaust seems to be the recommended size. My question is, are most of you converting the 2in to 2.5in at the manifold? If so, is there much being accomplished with the 2.5 in. exhaust? Assuming there is, how restrictive would it be to run about 2 ft of 2in pipe, then upsize to the 2.5? It's going in a 87 4wd dakota, and space for the 2.5 is tight. Thanks for your opinions.