At the local autocrosses I used to run at, there were about 5 of us at the head of the pack. I was one, a guy with a pretty well sorted LS swapped RX7 that was around 450hp, a guy with an Acura swapped Civic, and a couple guys with turbo Nissan's, I think a 240 sx and maybe a 180 sx, each of them making about 500-600hp. And then me in my little 7. Totally different cars, but we were all really close for times, and any one of us could be on top on any given day. It was a lot of fun. The RX7 and the civic were pure race cars, and the Nissan's were highly modded street cars.Our son spent a good bit of time and effort making his Miata optimized for auto cross. It really made a difference. with R rated tires, the shocks, springs, locking differential, the times were way down. He was competitive and when I drove it, I was in the middle of the pack. (Which was a big up for me, 15th out of 30 as opposed to 28 or 29th out of 30.). I was much quicker around the auto cross course than I was with my Corvette. Even being ‘just’ a C-5, it was way more power than I could use in the tight confines of an auto cross course. I really admire the young men and women who drive those on the road course. Takes skill that I simply did not have.
so, yes, I certainly agree, R rated tires do make a huge difference, however, slicks can get a bit dicey in a downpour.
Kristian