i have been modding these decks for over a decade i have not tried a timestep psu but tried the kab one and found miniscule improvements mainly in a touch of reduced noise and the tiniest gain in focus when listening to very dense classical and some old blue note jazz and some of my own productions.

you can do a dj mod that makes the quartz lock different and that is said to give the similar fluid presentation that some people have mentioned but when i tried this i just found that very complex piano pieces became less stable and sounded a bit more hazy in terms of the musical progression became less sure.

biggest differences i have found are funk firm platters better arms and feet.

all other tweaks were very expensive and only seemed to offer differences not improvements.

i tried the sds mat and found it very average.

i dont really rate the jelcos unless you are using vintage style denon carts and heavy headshells.

i have had great results with the roksan arms and the big sme arms.

also the mission mechanic sounded brilliant with an acrylic arm board and briar cartridge.

just my opinion though.