The discussion about modding rare cars is quite good, and I thought I'd jump in...
I have one of the 15 cloth/hardtop TTAs, with 3400 miles on the odometer now (I bought it in May with 2500 miles on it). It might not be a GNX, but it's still rare. And yes, I have modified it and am still in the process of modifying it further.
Blasphemy you say? Perhaps to some, but not in my book. Save for the muffler (the original was long gone when I got the car) all of my mods have been easily reversible bolt-ons, and I have all the original take off parts for the car with the exception of the muffler. I'm currently debating if I should put subframe connectors on it. I know that welding to the car will be permanent (no way can I hide the weld marks even if I remove the subframes later) but in my book some welding on the bottom is better than cracks in the roof. I bought this car to DRIVE, hence the reason I am contemplating the subframes. If I was going to trailer the car to shows and only drive it off and on the trailer, I'd never even consider the subframes. But, this goes for all my cars (present and future) it's not going to be some trailer queen no matter how nice it is. There are too many low mileage TTAs (and GNXs out there) that were bought, stored, and never driven. The owners have never really enjoyed the cars, because they just sit. I don't know about you guys, but I like to drive my cars, even if it is rare and low mileage. If I wanted shiny objects to display, maybe I'd collect antiques or something, but I prefer cars, and cars are made to be driven, even if they are rare and low mileage. I don't plan on daily driving it, but it certainly isn't going to sit.
However, while this might sound in complete contradiction to what I just said (even hypocritical), if at all possible, and given a car with multiple trim levels, I always prefer to see a base model or more common model with extensive modifications than the rare version with extensive modifications. I was looking for a cloth/t-top TTA originally because I knew full well I was going to modify the vehicle. However, the Cloth/Hardtop car came along at the right time and at the right price and I couldn't pass it up. So know rather than having a much more common car that I wouldn't have too much trouble modifying, I have a rare car which gives me second thoughts every time I consider another mod. This is why I'm drawing the line at a THDP as the last mod to the car. Because of the rarity I don't want to do anything permanent if at all possible, with the possible exception of the subframe connectors. I'm also beginning to consider that I might be happier returning my car to stock and selling it to a collector to be preserved and buying a less-rare variant of a TTA to modify, then I won't feel bad about modding a car with only 14 siblings and racking up the mileage on a low-mileage car.
On the other hand, I do have the TTA I've wanted for years, I've got most of the mods I'd like to do, and on top of that I managed to end up with the rarest version, so I'm pretty happy on all 3 counts. I'd love to go nuts with the mods and have a 10 second TTA, but I think I'll buy a GN or a Turbo-T for that, or possibly a higher mileage TTA.
As for a GNX... if I had one, I would modify it, but only enough so that I wouldn't be worried about driving it-- meaning put on a non-ceramic bladed turbo (shelve the original), change the fuel pump, hotwire it, and a scan tool. Nothing more than that.
I think most of us here respect the GNX enough to not go and tear it apart when practically every other TR has been. You dont(or shouldnt) just do that to such a rare and awesome car. 
