The RR has done that splicing thing since they came out. The miatas were doing it too. It only happens if you don't break them in gently and heat cycle them once before you romp on them. Pressures have a lot to do with it too.

I say the compound is the same because they act the same as far as heat cycling and they are the same softness. The RR is a little quicker cause it is completely smooth all around.