you must remember the q2 is not only about the improved performance
it will make you be able to drive with out the worry of your standard diff BREAKING (as well as the added safety q2 can offer in wet etc)
this will happen if you are driving the car at all how it is supposed to be driven..
if the standard diff breaks, the shards of metal will in-turn fly into the gear box breaking the teeth and potentially costing BIG $$$
now, im not saying that your standard diff will break 100%, but just remember that on top of the performance advantages, it also is a preventative upgrade.
in terms of handling, the best handling GTV i have ever driven was the PH3 3.2 V6. this had:
- blisten shocks
- eibach springs (i think 20mm lower?)
- anti roll bars (struts etc)
the ride was not crashy at all, infact it was waaay better than my 2001 standard suspension;
the steering was VERY direct and it handled like it was on rails, combined with the exhaust work that had been done, it was an incredible ride...
just depends what your absolute priorities are, at the moment im upgrading as things break... i just could have saved a few grand if i upgraded prior to them breaking (and damaging the gearbox)