Join Date: Jan 2006
Location: Barrington Hills, IL
While I do agree that a GT30R would spool up sooner, Garret does not make a T4 hot side GT30R. I can most likely get one specially machined, but at the same time, the turbo would really run out of breath in the top end.
When Yermancars converted to the smaller turbo he is running now, there was a small loss in power however, it spooled up so much sooner, and the power band expanded. The car felt quite a bit faster than before, even though its down a few horsepower from the GT40.
Also, the ball bearing turbos are nice, however, you will have to run and extra oil line through the water passages.
Standard journal bearing turbos, with updated housings, are a better way to go with the air cooled boxer motor in my opinion.