I'm sure a lot of the items on my GTA apply here, as the TTA is a GTA with a better drivetrain and much better badges. (hence why my nose badge is missing, someone stole it.)
Brake calipers - suck. Of course, I learned this while changing the rear pads and calipers out on the GTA, so I guess it doesn't really count, as the TTA has the 'better' design, so it's said. However, I'll be wary and approach that job only after a good night's sleep and a comfy mat to sit on while i work.
Ditto on the parking brake lever spring crap. If you haven't tried yoga yet, you sure will when you replace a caliper.
Ditto on hatch struts, but having a buddy to help (thank you, my lovely wife) actually makes that go by relatively painless. I can't imagine trying to do that one alone. How much does a hatch weigh again? Half a ton? I've yet to change hood struts yet, but a suficiently long broomstick seems to work just as well, and should be standard equipment with these cars. Throw in two, becasue you might have to have both the hood and the hatch open at the same time.
Ditto on aero fin. Both my cars have cracks on theirs and the mounting points up the hatch are totally trashed.
Power antenna? I've got two I need to replace. One just quit running, but the TTA's is running all the time so the fuse is yanked out. Which leads me to...
Multiple items running off of one fuse. HUH? Becasue i have no fuse for my antenna motor, I also have no interior lights, and the added turbo timer is ka-put as well. Previous owners should have ran juice form another fuse.
FOG LIGHTS. They look great when they work, but just try changing the idiotic H3 bulb out, AND get the lens back on intact. I've cracked one lens because the stupid moron-inspired plastic clips weren't on JUST SO, and the TTA's driver's light is just plain missing both clips. There is zero room in there to work with,unless I felt like removing the entire front fascia. I'm ready to go aftermarket on the GTA just to see what sort of set-up would approximate stock as far as looks but be so much more pleasant when it came to change a bulb.
Dash work - why, oh why is it so freaking difficult to remove the dash? You had better save every single last nut bolt and screw, too. I've only done this on other third-gens, but the TTA looks exactly the same. I'm also not looking forward to finding the burnt-out bulb on my GTA's Driver Information Cluster. Don't you love digital? Hopefully, the TTA's dash cluster comes out pretty easy, once I remove only half a million screws, to trouble shoot my boost gauge.
Boost gauge - Mine doesn't work. Waiting for a DMM so I can find out if the MAP works or not.
Little rubber vacuum/boost lines - why? These cars get really hot under the hood...
Ditto on fuel pump - see thirdgen.org on some people's hack solutions to that one. Cutting an access hole in the rear hatch area so they can go in from the top and replace it without dropping the tank. I wouldn't do that, though, it's hackwork. I'd probably pay someone to do it, though, rahter then drop the tank on my arm and try to deal with those stupid straps that hold it up and whatnot.
Idle - Not sure if this is an out-of-tune issue or what. At least it drives decently, and I can actually get on the gas now without it doing this curious backfiring-type-of thing. Boost rocks.
Gee, that's all I can think of at the moment... I guess this is the price you pay for owning a high-performance car. If you're not willing to scream and shout adn scrape your knuckles raw on some stupid part, then a high-performance car is not for you. Especially an American one.