I puchased a couple of Whipple Quad 3.3 Whipple packages for my new 604 c.i. motors. The package included Autronic ecms and wiring harnesses which came off a 600c.i. motor. My engine builder likes the M.E.F.I. 4b. It would be convienient and cheaper to use the Autronic system, but would it be a mistake?