It seems to me that there should be a smaller pulley for the S/C'er. Forgive me for not knowing, I have a Crossfire Limited and don't come over here too much. As far as a 13.0 @109 mph is concerned, the mph shows a mid 12 second pass, but with its gearing (I'm assuming it has the 3.25 our car has, right?) that's to be expected. IIRC, didn't that 13.0 pass happen on bald stockers too?