Go with the 10% if you want more power. There are many of us running the 10% with just a cat back exhaust, no headers, and stock cats, you'll be fine if you have headers!!!
Be careful though-- 10% pulley will increase chances of cracking somethign or blowing head gaskets especially if you have high miles-- my 95 SC is on its 3rd engine from some guy before me who kept putting a 10% on and cracking/blowing the damn thing apart-- dont wanna kill your fun though,, sorry--
Damon 95 SC www.cardomain.com/id/frozenrope