my next piece will be a higer density that older ones so i was just wondering if i find it to be too thick what is the best way of making it thinner? my old one is 60% and new one will be 65%. Thanks for any help

That should not be enough to matter, although density can vary. I've used thinning shears a bit here and there, mostly just worn them and natural shedding will thin it out over time.

Buy a Wahl Comb n Cut. I tried it on an old piece that I wasn't planning on wearing anymore. It is impossible to screw up, you just run it over your piece and it will magically thin it out. Do a little at a time, comb it out and if its not thin enough, do it some more. I ended up wearing that old piece for another month or so.