Seems like the MSRadon is lighter than the Hobbywing Pro stock V4. Also, they just came out with a new motor out which looks really good which won both stock touring car stock classes at our last club race. (see the last photo) (Actinium V4). I got one from my local shop (the one in the picture isn't mine that's brian's from Facebook).

There's also a new tire compound the SUV2 which was a lot faster/stickier than the old SU although wears a little quicker (I tried the 32SUV2).