I have installed several of them with absolutely incredible results in nearly every case. My reviews should be still in the AGN archives. No R7s but R9s, 95s, an 80, and just last week a 97 (see my post from yesterday.
I highly recommend them. BTW, I usually clip one coil off, usually end up with about 29 coils. Super smooth, no buzz.
I have the 12lbs PG4 in my 97. I used a little JM tar on the spring and moly paste on metal to metal surfaces. I applied some of the Vortek lubricant around the piston seal. Initially I tried 2 spacer washers and the firing cycle was harsh and the trigger pull was heavier. I removed the spacers and the shot cycle is now calm and there's no vibration. Eventually I'll change the seal to a Vortek Vac seal, but the factory one is working fine for now. I'm looking forward to accuracy testing.
I have the PG4 HO (High Output) kits in both my Tx200mkIII and my HW80, both in .22.. I have nothing but good things to say about them. Tom @ Vortek is very good to work with. The kits are well engineered, complete and simple to install. I would recommend getting the Vac seal along with the kit as they are way better than the stock seals. Deburr everything well before installing and don't over do the lube. expect about 100 shots till they settle in.
I replaced the factory Rekord trigger blade with a Rowan straight set back and its helped improve my shooting. My HW97 .20 was accurate with factory internals, but there was some noise and not as calm as I prefer for accuracy at longer ranges. After a couple hundred shots with a Vortek PG4 my it now produces repeatable accuracy with dime size groups at 25 yds. I have not had a chance to test it at >50 yds but the ability to follow through with a calmer shot cycle should help with accuracy.
I've installed Vortek kits in three rifles, A Diana 34 in .177, a 48 in .22 and a TX200 in .177, all full power kits and all made the shot cycle smoother and the rifles easier to shoot accurately. The TX200 has the PG4 kit and it slowed it down a bit, but the rifle is much better to shoot now. No more buzzy or twangy shot cycle, just a solid whack.