I know the SRT is legal, but there are genuine SRTs and what people call SRTs.
Anyway if it's legal in Mod order me one as I feel like trying to race something that isn't a Marchon in Mod, though it would be better if it were a 1.5" wheelbase chassis, body isn't important as I've got something that's lighter than anything Tomy make.
On the tyres front, rounded edges sound interesting, as do urethanes, if the urethanes have the grip they'd be better than silicones as you can sand them to exactly the size you want and they shouldn't compress under magnetic force like silicones do.