I have a 86gt cov stock , and I would like to put a surge perfomance chip that cost $199 but it is on sale now for $89 . Also I would like to change the rear end gears to 327 . What kind of perfomance would i get ?
Chips on Foxes for the most part are a huge waste of money. You can manually adjust spark timing in your driveway, and with an adjustable fuel pressure regulator, your A/F ratio. Also, down the road you will likely change your computer for a mass-air unit anyway, to compensate for big modifications.
Put 3.55 or 3.73s in it if its a stick car, 3.73 or 4.10s in it if its automatic.
The 86's have a very restrictive intake setup. Put exhaust on the car, then upgrade to CAI, followed by a 65-70mm TB. The upper intake can be swapped out for a later (87-93) upper, which flows better, and yet matches the bottom casting, which was the same for 86 on. The upper is a very easy bolt on swap, but if you want more flow, go upper/lower aftermarket or GT-40 style (Cobra, Explorer, or FRPP tubular).
Because its an 86, forget about new heads until you get new pistons, as the 86 has no valve reliefs on the pistons, and aftermarket heads will NOT work until you get that issue resolved, because of valve to piston interference.