GT PP axles/diff popping

So after multiple track days/autox and heavy mountain road driving my rear axles started popping and making noises at 20k miles. Not just a little bit of noise but noticable to my wife. Checked axle nuts multiple times, replaced wheel bearings/hubs, changed diff oil etc with no change. Replaced the half shafts with GT350 half shafts yesterday and the rear end is quiet as a church mouse now. Also replaced the diff oil back to 75w90 RP. Hope it stays this way. Anybody else experiencing this?

Car is base GTPP stock engine/tune, suspension mods in sig. Built 10/31/14.

Mine is non-PP but I had some clacking going on in the rear axles - they didn't tighten the CV's up to spec after dropping the subframe. Maybe they're loosening over time?

I checked the torque on my axle nuts everytime I took the wheels off and they were tight after I replaced the wheel bearings.