IMO the RB20 only do better than SR is smoother, the SR is a bit rough.
The RB sounds better too...
But other than the SR is better at every area.
lighter & shorter allow it to sit closer to the firewall for much better balance, handling and stopping.
it perform better both on/off boost, and late model SR also have VVT.
more torque is obviously the most important issue for shooting out the corner, i agree the RB might able to rev higher, but why need to rev the shxt out of it when u can get it in lower rev?
i am interest if someone can post up some dyno to see which engine has wider power band.
when someone say RB20 is cheaper to build, i am not really sure, since we are talking 6 piston, rod, injectors and SR is only 4.
previously own a R33 RB25 and the S15 SR20 is possiblily to compare with it.