First off...welcome to the board. I'm a little biased...so I'm gonna say a GSR. Difference between the 94-95 and the 96-up is the emission controls. the earlier models have OBD1 and latter have the OBD2...the latter is a lil more strict when modifying since the engine is a lil more sensitive due to stricter emission systems.

As far as bang for the buck...I'd go with the GSR because there's a huge market out there for them, and the GSR motor (B18C1) has been proven to create mass amounts of power. 12's are doable on either car...it's really what route y ou want to go with and how much you have to spend. A turbo is great, depending on mileage, get a leakdown test, and I'd probably do a major service before installing it, as well as changing the belts. ( that's just being safe) Greddy, Rev-hard, Drag, are all good brands. Supercharger is another great system, Jackson racing is a proven manuf of them as well as Vortech. Another route is all motor, which costs more IMO but gains alot of respect, especially running 12's all motor. (that's DAMN good)

IMO, I like the interior of the GSR a lil bit more than the Mitsu and the body lines as well...it's up to you ultimately......good luck