I was looking to build a custom catback exhaust, and I want to know where I should start. The 535i's exhaust is a bit different from what I've seen before. It starts off with a y-pipe, one pipe that splits into two. Does anyone know what diameter the inlet pipe is, and outlet pipes?
http://www.ebay.com/itm/3-2-5-Y-Pipe...052825&vxp=mtr
Is this the type of part I would start off with?