well firstly, you arnt going to get 400hp on a t3

you may just push it on a t34

secondly, there isnt any point in going external wastegate in my honest opinion.

your better sticking with your interneal wastegate and actuator. you can get good enough boost control with a set of air injectors

really, when your going for 500 + bhp then you would start thinking about a external wastegate setup, but like i say to be honest there isnt any point in going external

jim