Hello,
I'm so hurt. You asked me but my answer wasn't good enough? Sheesh. =D
Changes are minimal aside from styling inside and out. Everything is compatible - even the dash (but what a bitch to change out the whole dash). Obviously, to change the hood would require new headlights and bumpers. Everything else is the same.
The chassis is the only real change. The stiffening was something like (marketing hype, watch out) 35% (what's that really mean? - in terms of performance? I dunno).
If you're serious enough about performance for that difference to mean anything, then you're serious enough to have a roll-cage and that'll more than make up for the stiffness difference. If you're not that serious about every last bit of power and handling, then you won't notice the differences in the chassis.
Joel