IMHO, Normal break in, nice and easy creeping up to a race tune is the best. Takes about 3/4 of a gallon, some time and restraint but you will be rewarded with an engine that lasts and keeps running and running. Don't forget to pre-heat! I typically get a good 6 gallons of racing before needing a light pinch. And I run my engines hard, my low profile headed Nova's are running about 280 when temped, nice trail of smoke and crisp bottom. My Fusion X5R regular head runs 250 to 260 with same characteristics. Byrons 30%