It is always good to be learning in this game, that is all .

The exhaust flow is something I was aware of with External gates but not fully.

I was only referring to the wastegate being shut with my previous car (1991 Porker 944 Turbo). Running at 15PSi (over the stock 10PSi) it would very gently drop to 11PSi at the redline, something they all do even as standard. Shimming the wastegate (and plumbing in a 'boost profiler') helped but did not cure it. Going to a dual port wastegate did keep the car holding 15PSI to the top along with less turbo lag and another few horses at the top end as a result. I guess the principles were different there .