I upgraded my Rega Planar 3 (2016 model) with the following:
--Groovetracer Reference Sub-Platter (w/cubic zirconia ball) ($275.00)
--Upgraded White Silicone Belt ($40.00)
--Groovetracer Delrin Platter ($350.00)
--MCM Sorbothane Aluminum Feet ($129.00)
--Rega Neo PSU ($395.00)
--Rega Ania Pro Cartridge
--2" Acrylic Isolation Platform
I also own a stock Rega RP8 with a Ania Cartridge. The upgraded P3 doesn't 'blow' the RP8 away but it certainly is its equal. I tried the RP8 with the Ania Pro and the vocals were too sharp for my taste. I then switched the cartridges and found that the P3 as upgraded made the Ania Pro more comfortable to me.
I realize that the turntable upgrades above were nearly $1,200.00 but I only paid $995.00 for the Rega P3 and the $2100.00 invested makes it sound as good or very close to the $3,000.00 RP8.
I think upgrades should be done auspiciously and carefully. Frank Smylie at Groovetracer makes an amazing product that is often better in quality and design than the mass production of Rega Tables--with each table a compromise of something to fit into a particular price point.
Are Rega cartridges the final word in music production? No. Of course not. Roy Candy, Rega's founder reminds me of the late Steve Jobs--his minimal plinth philosophy and his engineering focus creates certain proprietary goals for his products. I think Rega Cartridges, especially the moving coil selections, are excellent when coupled with a Rega Table.
In any event, my upgrade success story is based on my subjective ears--others may find a different path. The great thing about an Audiophile hobby (my family refers to it as an addiction) is the individual enjoyment of the music. Cheers.