If its an all orginal 84 GN. I would start with the 86/87 ECM/MAF swap and an 87 Coil Pack and with that, add a scanmaster or powerlogger. Boost guage, and knock guages are nice to have. Grab a fuel pressure regulator, adjustable wastegate actuator, and a hotwire kit with a new 340 Walbro Pump. Then go with a Cold Air intake, and new Comp 980 valve springs. These upgrades will wake up the car. If you want real speed, I would get ported intake, ported heads, 3" downpipe, TA-33C Turbo, Razor's Alky kit, Wideband O2 Sensor, and a Turbo Tweak chip to match all your parts. I think others will confirm this is a good set, I am not the most experienced but this Is what I see for the most popular upgrades..