Noobs!
350-400 or a blown motor or two trying!
260whp now.
Header back exhaust (minimum gains, i would PRAY) 20 hp.
Tweak Stage 2 tune (maybe even a 'high octane' tune) 20 hp
Cams & 10:1 compression pistons, ported blower, ... 30? 40? I really dont know for sure... but you see where I'm going with this...
I don't think any of those are inflated estimates for possible power gains from this car. I could be wrong... I haven't even touched on a few things out there... so hitting 350whp should be pretty attainable for anyone that wants to spend. The only thing in that list that require SERIOUS work is the pistons. Leave those out, and you should still be able to get nearly the same with more timing or boost, or something...