EtoS

I'm about to happily purchase a blue pearl 5 speed WRX TR. But I also got a few questions as far as what I can do to the car and how. First off I'd like a boost gauge but refuse to pay nearly $400 to the dealer for something so small. I have a boost/water temp gauge off an 86 SVO mustang I'd like to use- both are electric with the water temp gauge having a water line to it. How would I put this gauge in if I can use it on the TR? I can respond with more info on it if more is needed. 2nd is the cd player. God this stock one sucks- how hard would it be to put in a new one? I'm not looking to put subs or amps or anything of that nature, just an MP3 cd player. 3rd's a bit tricky. For those who don't know about the TR vs WRX, they're indentical in performance but they basicly stripped a WRX of good seats, good cd player, spoiler, fog lamps, ground effects, and reduce the price not even noticebly by $1000. I really liked the WRX seats and would want to switch those in. Why not get a WRX? Cause they only have limited edition ones that are nearly $4000 more then a TR and it would take 3-4 more months for a normal WRX cause subaru had this bright thought that no one wants a normal WRX over a TR so they didn't make too many WRXes(I checked 5 dealers and none had a normal WRX in blue pearl- one had it in grey). Where would I find stock WRX seats and how would I put them in? 4th is what's some good bang for the buck performance items I can add to this already insane beast. I've heard stories that with as little as $700 the HP on this can be raised to 270+ with a bit of tuning.