Quote Originally Posted by integral90 View Post
Ultimately up until the split a single and dual outlet catback run the exact same course and you're right when you say the main problem is in the split but you'd assume a good aftermarket exhaust would have a good-quality split that won't disrupt flow that much. But a single outlet exhaust still has to bend in the same place at roughly the same angle as one of the dual's. What's the say it's impossible for the gas to flow as well if it splits before the corner as if it just stayed all together around it?

Not saying you're right or wrong but just looking at it from another perspective
Well if the gas splits after the Y wouldn't the energy/velocity of the gass travelling through the pipe is also split into two. It then has to travel through twice as many bends and mufflers before it exits the system. It adds complexity and that hinders flow for sure.

A well designed dual outlet should be able to flow very well, I'm just saying a single outlet exhaust shouldn't be a restriction by the simple fact that it is single outlet. (from the research I've done there should be no performance benifit of going to a dual exhaust if both systems are well designed)