Stage 1 gives about 270 bhp, which is faster than most Scoobs anyway. There isn't really a stage 2, but next step is stage 3 which gives about 320-330bhp and involves different injectors and a 3 Bar MAP sensor to be added and a different chip again. Reliability can be a bit dodgey at this level, with rear diffs blowing if you do launches. You also need a breather kit, and at least a 4x4 if not an RS500 intercooler at this level of tune. Standard turbo's won't last long either, so a T34 hybrid is ideal.

Personally, if you are used to a Scoob, and 4x4, a stage 1 Cossie RWD will scare you to death anyway, and if it is your only car, will be much more reliable IMO.