If your looking to go from JL motors to Nova based motors, be prepared for a much longer break-in time. The JL's after 5 or 6 tanks are fully broken in. The nova based motors will take between .5 to .75 gallons of fuel to have a good well broken in motor that will last. When switching to Nova based motors... make sure you buy the mfr recommended pipes... and be prepared to drop pinion size one tooth for 1st and 2nd gear. These are things you probably already know, but I just thought I would throw in my own observations.