Originally Posted by sykes
In the magazine there is also a complete guide to wastegates and whether internal or external are better! The conclusion from it was an external 1 because the flap is that much bigger ands the exhaust gases escape quickly thus reducing them being sucked back through the compressor wheel and controlling the boost level better! I can't remember properly I'll bring the mag home from work and check what I've said!
The theory is reasonably true, but on a low/moderately powered car, an External Wastegate just isn't needed.
Mine's running 350bhp on an Interally 'gated turbo and it's only now I am considering going to an External 'gate.