turbo help

The upgrade your speaking of is somewhat simple.

The exact specs on the 84GT have slipped from my mind but ill give you what i know

The differences =

35lb injectors aka brown tops (you have 30lb green tops)
-Found on 86-88 turbocoupes and 86-89 xr4ti's

VAM-air meter, you have a small vam, they have a big vam.
-Found on 87-88 Turbocoupes and all SVO's

Intake(?) If you have the upper/lower Inline intake, the later model svo's came with the "square" intakes.
-You dont have to "upgrade" this in perticular

Computer The better svo's came with the PE's series computer,the good turbocoupes came with LA/LB series computers.
-You will need a PE/LA/LB series computer to correctly run the BIG VAM and 35lb (brown tops) injectors.

Fuel pump The svo's also came with two fuel pumps (intank + inline).
-You dont have to go with the inline setup, just put a decent 255lph in the tank and your good.

Camshaft The Svo's came with a hotter cam profile.
-Stick with what you have until you've done the above, id suggest going with something aftermarket if you go through the trouble.

Intercooler Stock mount wont work well for you.
-Go with a front mount intercooler (better), for a mild(stockish)build, i recomend the Volvo intercooler(cheap and good).

Thats about it that i can remember. Most of this stuff can be had pretty cheap used (i wouldnt buy the fuel pump used!!! )