Holley sniper failure, this time its all bad.

A few years back my friend built a 40 Merc with a 540 twin blowers and Holley FI and he had a 4 speed Lenco, and every time he would shift gears it would back fire and blow the belt off. I worked for Cadillac for ten years and I know how fuel injection works, that said, I kept telling him the set up would not work because it only uses a TPS and MAP for fuel delivery. He said Holley said it will work and they have thousand out there to prove it. The problem is with his set up he will be cruising at 3000 RPM and grab the next gear and put a load on the motor without giving it more fuel IE stepping on the gas pedal, so it leans out and back fires and that brakes the blower belt. It needs a mass air flow sensor to work and nobody uses one, if the did the systems would work great.

Oh yea just to add he trashed the FI and bought 2 Holley 650's and it runs like a champ,