Did you beat the initial playthrough? If so then yeah. TVHM will start a new playthrough for you, and it will be noticeably harder. After this playthrough you should be hovering around level 50. UVHM is insanely challenging, and basically requires the use of Slag (as it triples damage in UVHM instead of doubling it), because enemies have an insane amount of health. It is a final 3rd playthrough, and easily one of the hardest games I've ever played. OP 8 is just the dev's way of stretching the game out. It was annoying to have to regrind all the gear 8 times. Didn't do it, but each OP level comes after UVHM and you have to earn the next one on Digistruct peak. Hard as well, buuuuut like I said.. They raised the level cap twice and I had to regrind twice. Not 8 more times, no. Cap is 72 m8. Have fun!