Have you scanned it for error codes, whats the millage, and what other engine mods does the car have?
I just picked up my bmp gli and drove it home 213 miles. It has a new south boost gauge and at full boost its over 25psi. I've herd of k04s boosting 25-26 but its but the needle is barred so Im not sure how much its boosting. Also when I get on it sometimes it will only make 5-15psi. Im thinking Its the n75 but not sure. Any words of wisdom or past experiences welcome.
The H and J are OEM N75's tho. I'd honestly pick up a MBC and bypass the N75 to see if that'd help also. Only $50 or less (look in classifieds) for a MBC kit bro.
I know all cars and chipped cars are diff, but I was always under the impression Revo and APR worked well with H valves and GIAC worked well with the J (based on the trends I've seen over the years with ppl posting which valves work best with their chip, so take my observation for what it is).