Good call Rick Lake, and it's not always 'just horse power', gearing is also a major factor when it comes to tire slippage. My old Excal, STOCK 302, ultra low 1st gear 5 speed with a 3.5 rear was more 'squirrly' than my ERA with easily twice the horse power! In both cases I HAD to get the best traction tires I could find just to stay on the road.
The ERA gearing is much higher than the Excal and that alone is a huge factor in putting the power to the ground.
I'm ready for some new sneakers myself. I've seen David K. mention those Avons several times. I sure love the Bill Boards, but am considering the Avon's (I feel all dirty somehow having said that...)
I'm still not convinced drag radials are the way to go as far as a good road course choice though, but admit, I've never tried 'em.