Ok I've done almost everything I had planned on to the car for this year which is everything in my sig. The only thing left is the smaller pulley. I'm going with a 3.5 as recommended from ZZP but I have a few questions.
1. What (if anything) will dropping to a 3.5 do to my MPG.
2. Will I need a smaller belt or will the stock one do fine.
3. When I order the pulley from ZZP I will also order the puller (Rent it that is). My question is do I need to also rent the ZZP backing plate? What is it for? I'm going with the modular set-up because who knows what the future will bring (Rockers / Cam).

 

i was also thinking of doing the pulley swap, on my 05ss supercharged, do you recomend zzp, or have any comments or advice?

 

Before you jump into it- I'd find somone local to scan and be sure you have no knock (or buy one of those aerforce gauges or something). If you have even the slightest knock now, when you drop pulley sizes it will get worse- and you won't be any faster. You should be able to run a 3.5" knock free, but its well worth it to check first.

You won't notice a difference under normal driving. With the bypass valve open (normal driving)- the s/c consumes very little power in comparison to when you're in boost, and the slight rpm increase isn't enough extra draw to notice a mpg change. At wot, it will obviously be worse- the extra rpm under boost draws more power to turn, and the extra power uses more fuel (obviously b/c you're pumping more air in); but for normal driving, it won't matter to mpg.

I had to goshorter with my 3.4, not sure on a 3.5"

No backing plate- its for removing the modular hub if you were trying to return the car to stock. That puller is the best I've found, and I love it. I actually bought mine for doing pulley changes for locals and such. Modular setups ftw- I just kept my eyes open on clubgp, and have picked up pulleys for it for as little as $20 shipped- so its easy to build a nice collection.

Either way- modular or press on, zzp makes nice pullies. I haven't honestly seen any pullies that I would necessarily avoid- its a pretty simple piece. I do prefer the zzp modulars though, because they have such a huge variety of sizes.