Well, the only IEM I have to compare the Pistons to are the Monster Gratitudes. And surprisingly, the Pistons are in the same ballpark.
When I first plugged them in they were bass heavy, but that cleared up in a very short time. They have a good amount of bass, but now they aren't bass-heavy. They do sound a bit warmer than the Gratitudes to me and have just slightly less detail. That's probably from missing the slight edge that the Gratitudes have to their trebles. The new Pistons are smoother.
I like them quite a bit. They're far better than the Deltas, which are the last inexpensive Chinese IEMs I had. For the cash, these are tremendously good IEMs.