I will add that my JL is hand lapped. Right now I stand at about 4 gallons but all 4 gallons have been with a full on race tune. i idled one tank and cranked the needles to full power. Neal says you will probably lose some longevity but I think of it this way. 8 gallons of full race tuned usable power, or 1 gallon of break in, retune, and then 8 more gallons of full race tuned usable power. you can keep that first gallon if you ask me. I would rather throw it on the track and race it out of the damn box then sit over it with a heat gun for 1/2 gallon and then putt around the track for another half gallon following it around with my sisters blowdryer..Give me power now and keep your extra gallon or two, especially at the prices of most of Neal's engines