The car just revs quicker. FWIW it bogs a little if you shift into a gear under 2000rpm, but it's very easy to get used too. As for the underdrive pulley- to tell you the truth I didn't really notice much. BTW all the problems with Fidanzas have been on higher power TT's...I have yet to see/hear/read about any NA's having problems. My Fidanza has been drag raced, auto-crossed, roadcoursed and is driven on every day