Originally Posted by snrusnak
There's two reasons bringing the exhaust pipes together is good. 1) when the left and right banks are connected down stream in the exhaust it equalizes the pressure and the motor runs more "even" from left bank of cylinders to right bank of cylinders. 2) This is the main reason, when you take two pipes, with gases flowing through them at a certain velocity, then merge the two pipes together into one, the velocity increases, and this helps "suck" the exhaust out of the engine, increasing power potential. "Back in the day" true duals were considered the best because everything came from the factory with two undersized down pipes from the manifolds slamming into each other (not a good flowing y pipe) into a single, even more undersized, exhaust pipe. Obviously, if you take your truck and take the down pipes from the manifolds and y-pipe them into a single, half inch exhaust pipe, that will not flow well, lol. Technology and availability/ease/affordability of aftermarket thrives nowadays.
I'm sorry my question must've been a little ambiguous. I completely understand the purpose & benefit of a crossover on dual exhaust & how that effects scavenging. I'm wondering if there is performance advantage to adding a single to dual kit on a single exhaust setup. Basically, exhaust manifolds to single cat, single downpipe, single muffler with dual outlet and two exhaust tips. I know the kits look great, but it has always been my understanding this is a cosmetic upgrade, at least in hotrod/musclecar circles & was wondering if that was no longer considered the case.