mods, these turbo's spool exactly where they are supposed to. If you want quick spool than the stockers or 530's will help you achieve that. The 600 will have some characterics of the 530 as well and some of the the 700, which is why they considered this the turbo that bridges the 2. Lag is a little more than the 530 but less than the 700 and the 600 will have a tremendous amount more top end than the 530 (obviously not as much as the 700). Just depends what you goal is.
I find lag to be minimal, especially considering the top end, but to each is their own.