ORIGINAL: z28pete

Underdrive pulleys on an LT1 are a waste of time & money, the only things driven by belt are the alternator, power steering pump & the AC compressor. The alternator only draws as much power as is neede to run the car, the AC compressor does nothing when the Ac is off, the power steering pump only puts on a load when the steering wheel is turned. The water pump is the biggest power drawing acessory and it does not use a pulley because in the LT1 it is gear driven. You can save a few horses at hig RPM by converting to an electric water pump, get a street rated one rather than a strip only one. Apparently you did not take a good look under the hood, you already have elecric fans. The air foil may get you 3-4 HP, the 52 mm throttle body will do nothing for power until you get to around 400HP and the engine wants the extra air. If you have a A4 transmissio go with the 3.73 gears, if you have the M6 transmission go with the 4.11 gears. If you just want to drag race, go wth 4.56 gears or 5.12 gears, but the the stock rear will probably break.