the Pullies were a great addition if you ask me. As I stated in another post, this is the 3rd car I've owner with pullies and hands down the Civic Si responded the best. throttle is much more sensitive and responsive. I'm not one to buy into all the vendor hype regarding horsepower gains, as both procivic and importdps claim 9-11 whp gains from these. I would be confident in saying that I believe the gains recognized by numerous 8thgen members showing anywhere from 4-5 whp across the power band. To me, it does feel a little stronger than that especially in the mid-upper rpm range. I can't wait to see the new edyno figures to see if my suspicions are confirmed. A great part for the money.