what head do u have. Nissan GX Head is good it has larger everything so if u port and polish, add double valve springs, skim it to up the compression and flow test it u will notice the difference. i cant rember what cam it had but it started pulling from 3500 - 7000. to achieve 105- 110 hp is not EASY but its do-able. also what fuel do you use? Avgass?