I haven't seen it mentioned here on any diy but how exactly do you remove the a/c pulley? The alternator and crank bolt right off but that third pulley has like a cover plate. Assuming I'm even working on the right pulley.

 

you don't remove the AC pulley. the set should just include the crank pulley, alternator, and the one you have on in the middle that looks like a water pump pulley, but is just an idler.

mine is the set from AMS, looks similar to yours. And they aren't underdrive, per se.. same size, just a percentage of the weight of the stock pieces.

make sure you pay attention to the running of the engine after removing the harmonic balancer (stock crank pulley) it can introduce vibration and cause internal issues.. not saying it will for sure..but can happen

 

I have a 06 G35 coupe rev up 6-speed with lightened flywheel and a high output alternator and idler delete. Do you think it would be safe to put a underdrive crank pulley on? Has intake plenum spacer, bigger throttle body and spacer, intake, and full exhaust?