they're good pistons, just heavy and mis-matched. You will have to weight match them. I've seen them off as much as 10 grams either way on one set. As far as quality, they're alright, of course they arent the best, but then again, you get what you pay for in most cases.
Used to be that TRW forged pistons were the ducks guts but there are a few companies that make better(as in more expensive) pistons. Light weight forged pistons are the do wah ditty now days. I'm still running my old hammered on TRW's. They have lasted over 10 years, 2 rebuilds, some valve touches, a leaned out detonating motor and some flycutting and are still going. Maybe they should call them energizers instead, LOL.