I agree, i'd rather deal with the poping than replace bearings as this was just recently done. I replaced the restrictor last night to the recommended size & will try it soon. Will report on the results.

Yes the poping does go away when throtle is applied - so I think you've hit the nail right on. Also, the appearent hot spot goes away. The turbine runs great thoughout the rpm ranges & the temp is perfect. I run the 2-pc pipe & find that it works the best. ~490 deg at idle & ~590 at FT.