[Chris@Apex]

External will be needed at higher hp numbers, like 300. the problem with internal is once boost is applyed to the diaphram over comes spring pressure the flap starts to open, this could be as little 7 psi on a 15 psi set wastegate. External you have a boost on the top side of the wastegate, so it holds pressure in side the gate tell you boost level is met, higher then what the spring it set for. And there much more accrete at setting boost levels, any one that has been in a srt4 knows that the boost is always up and down at wot. tis is part to the computer controlling it and a very week spring in the wastegate, 6psi.