Gutted cat/ test pipe

[VinPecora]

Which is better to do, any differences. Can I do either on a stock turbo car, with a freeflowing exhaust, or will it overboost??

 

[TURBOV6]

A little difference not a whole lot, let it flow freely as possible, faster turbo spool up and will noticed a slight boost increase, so you will need an adjustable wastegate and fuel pressure regulator to compensate.