RSR's were about 1 second quicker than the ku36 around lakeside for me. they did chew out a lot faster as i was driving them on the road aswell, but that sounds like a pretty awesome deal, DO IT !
as a comparison, KU36 felt nicer as you approach the limit, the RSR's felt a bit funny and did not give as much feedback, but had better overall grip so thats the tradeoff.