Wilkinson, but I've never had any kinda trouble with a strat-style stock bridge; what problems are you having, to switch it out? It might be fixable.
Your not set up properly then. Strat bridges work fine! Your spring tension could be off, your nut may be binding, not enough wraps on the strings posts etc,
Moving on.....
Is it tight to the body? If not, tighten it so it's tightly flat against the body using the springs in the rear cavity. That should help.

Otherwise, I would suggest tuners might make more of a difference, especially if it's not an MIA, try schaller lockers or something.

But if you're saying that it doesn't stay in tune with USE, then, that's perfectly normal and there's not an awful lot you can do, as you adjust the string tension with use, and without a double locking trem (which will cost quite a bit, and be difficult to fit), there's not a lot you can do about that.
Quote by a7xrocks02
It's a Fender Mexican Strat. The $400 one.

EDIT: Yeah, its probably the setup. I'm going to get it set up very soon so that'll probably take care of it.

Ok well there you go. If you end up still needing to get a new system though, I'd go with a Wilkinson trem, and some locking tuners to go with it.