Why change the factory Y pipe? I am thinking about the vortex cherry bomb any thoughts on this?
Take a look at your Y pipe where the two pipes meet into one, they are almost crushed. There is a restriction in that joint. A good aftermarket Y pipe is mandrel bent (No collapsed pipe), and the joint is mitered together to keep a good unrestricted flow of exhaust. This in itself is a huge performance improvement over the stock pipe.