They should've made the gearing in the Auto GTS a little bit shorter. that way, you could time the shifts in M mode to keep it in lift better, only in gears 1, 2 and 3. 4th gear should stay as it is pretty much (as it's the overdrive gear, and the odds of hitting lift in 4th on the auto GTS is pretty much a pipe dream) but being able to rip through 1st, 2nd and 3rd in lift would give a huge boost in performance, by the time you hit 4th gear the tall gearing would bring you up to top speed fairly quick at that point.
On top of that, they should've kept the 2000 model year's redline & fuel cut where it was for ALL model years, the ECU swap is a bitch, and the lower limits did nothing but hurt the performance of the automatics out there.
I think toyota should've shot for a nice round HP number, hell, 200 HP isn't too much to ask, why stop at 180 HP when 200 was easily acheivable under US specs? (Lotus did it with a domestic 2ZZ, why couldn't toyota?) The GTS could've come from the factory with a TRD
header, exhaust, performance filter, and matching tuned ECU to do this.
Thicker sheetmetal in the door skins would've been nice, they're about as dent resistant as a soda can!
How about making the rear strut tower brace a factory item guys? the 350Z has a brace from the factory and WOW! not only does it stiffen the car, but it looks cool too (all wrapped in leater... Awesome!)
At the very least, they could've stich welded the unibody more to increase ridgidity.
Lastly, The GTS has a 4-wheel ABS disc brake setup, but it still retains RUBBER brake lines!!! What were they thinking?!? high performance braking needs stainless braided brake lines, or at the very least, steel hard lines. Such an awesome brake system, but with those rubber lines, the brake pedal is mushy and feels cheap, brake performance also suffers.
As with any car, there is room for improvement, however, if there were no room for improvement, there would be no aftermarket for our cars...