I am not going to contradict Eds comments but I run this thing inverted on a 60 size P-51 with a Jett Pipe on it and 14/14 apc screaming the )(*&^ out of it for a year now and no problems. I think a large part of it is "proper adjustment". I cannot tell you how many people I run into on a regular basis who think they have their engine dialed in when it is still way off.

Revving up the engine after each adjustment, does not tell you everything.