Well, Laylax is the middle of the road brand for VSR upgrades, and PDI is a bit better, is what I have and IMO is worth the extra money, and you cant go wrong with it. for a total PDI rifle, it is going to cost you around $500 for everything, if you buy a Z-Trigger. You should be fine with just sears, which is what I'm running with at the moment and they have lasted a couple thousand rounds on a 530FPS spring.