Hey Adam93tsi,
Just wanted to warn you about adding those mystery oils to your engine. I'm not sure if I've mentioned this yet, but my buddy has a 3kGT VR4, and he recently added some kind oil additive that a mechanic said would get rid of the ticking. So he did, and the ticking went away. 2 weeks, later, his engine throws a rod. Coincidence? Maybe, but he's looking at ~$5k for a used engine now. Becareful what you do with what is essentially the lifeblood of the engine. Just because it stops the lifter tick doesn't mean it's actually doing something good for the engine.
My recommendations, short of swapping the lifters, is just to keep the engine clean(flushes, more frequent oil changes), and experiment with thinner/thicker oils. I wouldn't add any additives. Hopefully, if you keep your engine clean enough, deposits that might be blocking oil flow to the lifter might get cleaned out etc. Good luck.
Oh, and Vineet might have some insights into the 3kGT engine, ticking etc, since he has a Stealth RT/TT. Any comments Vineet?