Would it be a good Idea if I put a lighten crank pully with my 17percent alta sc pully, a unichip, detrot by pass valve, Dinan intake, and a custom catback exaust

 

yeah, but only if its the same size. you dont want to be messing with your alternator and ac compressor rpm. as long as its the same size i would go for it!

 

would a stock size alta crank pully make a difference?

 

A light weight crank pulley may be hard to "feel" in the seat of your pants. It would show on a dyno, but not really sure how much if any at all.

If you run the Alta or Craven 2% crank pulley with the 17% SC pulley you have now you will in effect put a 19% pulley on the SC. You may or may not feel that 2% gain under foot. It would show on a dyno. Just be sure to get the alternator pulley too. Click here and look about half way down for more info about the Craven pulley http://www.autoxcooper.com/craven.html