My friend bought one of my Edge convertors from me and sent it back to them to have it spec. to his motor. He ran 3 10ths quicker when he got it back and ran it. I cant remember the guy I talked to at Edge (been about 6 years) but he had 30 years of experience with racing convertors and had worked for some of the bigger names out there. Great convertors. Forgot that they quarentee quicker times or your money back. Is yours a 9 1/2 inch also?