When my car was first tuned to stage 2 just over a year ago I had the NGK 7437 plugs installed "racing plugs" recommended per APR website. They lasted 15k miles and were great but pricey. This time around I ordered the RS7 plugs, $52 from DAP with bonus points. Honestly, driving around with the RS7 plugs for a couple weeks now, the car does feel a tad less manic, a tad bit slower, a tad bit urgent. I really didn't think there would be a difference at all but there is in my experience between the 2 sets. Now, I did save $100 this time around and the car is not slow but it really does feel just a slight bit off from running the racing plugs. Nothing wrong with either set of plugs for tuned cars. If I happen to have an extra $100 to throw at plugs next time around I will likely get the 7437's again. Not sure if the gapping on the RS7 plugs is what is making the difference in feel and performance. I have them gapped at 24 just the same as the racing plugs were at the time of use. Just my 2 cents from personal experience.