well a few hours ago...man could I notice a diffrence! I don't know about you guys but it made a big diffrence to me. It improves the smothness A LOT! and over all felt great! I would recomend this to anybody, for $40 its well worth it! Sparkco (Peter) was great to me and my package arived promptly. I am very happy with them. My only gripe is that I can't put the valve cover's cover on now, aah well a small price to pay.