Rega P5 Upgrade:TTPSU,Platter Or Subplatter?

I have read about Groovetracer acrylic platters and subplatter Reference being an upgrade to the stock ones in the P5. I've also read about better counterweights, one of them being Michell Tecnoweight to improve on the stock stainless steel counterweight on the P5.

Just out of curiousity, which upgrade below will yield the highest degree of sonic impact in chronological order?

1) Rega TT PSU
2) Groovetracer subplatter Reference
3) Groovetracer acrylic platter
4) Michell Tecnoweight counterweight
5) Clamp

Anybody tried an aftermarket acrylic platter on the P5?

Any opinions would be appreciated.