will changing my distributor to msd and adding the msd-6 box and a good set of wires add any horsepower.i've got a 78camaro with a 454.can someone explain underdrive pulleys to me.my alt.belt keeps jumping off at high rpm's.would underdrive pulleys take care of this problem.summit has a aftermarket alt.bracket i'm thinking of buying.my brackets are all big block brackets but the alt.still seems to be off just a little bit.i've tryed shimming with washers and it does'nt matter where i put them it still throws the beltthe bracket that comes from the water pump looks like it needs to be a little bit longer(1/8").these brackets came with the motor.

 

Underdrive pullies just change the turning ratio from the crank to the accessories. It just slows down the final drive to use less effort/power. They will not necessarily help you with your belt coming off unless you have a bad pully. Have you tried putting on a smaller belt? The MSD ignition should keep your horsepower more consistent and it will give better throttle response and let you go to higher RPMs if your valvetrain will let you therefore resulting in more horsepower.

 

I use the MSD HEI conversion with the external coil on my 454. i picked up some RPMs and it seemed to run smoother.

Greg