ahh...I didn't know Kawie had put out a statement about it.
if it's just detonation/pining, which is what it sounds like by your description, you could try upping your octane a bit...by mixing 25% VP-C12 and 75% pump fuel for your pre-mix.
there are a couple members on here running "R" models...our member zz3gmc comes to mind 1st...he may know of the report Kawie put out, and know what was done to cure it...you can try sending him a PM.