Im getting my 88 RX-7 Straight piped pretty soon, the cat is gutted, car is N/A and completly stock, along with the pipes, ill be getting 2 mufflers thrown on aswell....What I was wondering Is what Size Piping should the 13b go could with? I heard they need a good amount of back pressure to operate decently, and the Shop Im going to kinda needs to know haha.

All help is appreciated, thanks!