I have learned so far with external or internal, external is the way to go. Yeah, internal may work for your combo now, but external is alot more controllable and accurate. But if you go external, you want to go off the header, not on the down pipe. With my t66 combo etc., I could not controll boost at ALL with internal, it would just push that little puck open, blew head gaskets and all. Goodluck, your combo sounds good.