Hi Roy - you are gonna have to give me some R32 performance tips now mate.... ha ha
I look at it like this - You can make a GTS-t and a GTS-4 more powerful by upping boost, etc yada yada.
You can't easily change a GTS-t into an AWD car - But you can easily turn a GTS-4 into a Rearwheel drive car.
You can lighten a GTS-4 by stipping down stuff A/C, Hicas, Seats, etc - If you are really serious....
I reckon (my opinion only) it wouldn't be too hard to get a GTS-4 to outhandle a GTS-t.
The other advantage of a GTS-4 is that once you have flogged the crap out of the motor - just f drop in an RB26 and you have a GTR Nice....
4 Door R32 GTR coming right up :)