So I bought this '90 GTUs about a month ago. It has a carbereted high bridgeport 13B rotary, on top of a few other upgrades like exhaust, clutch, short shifter, etc. what performance upgrades should I go for next?

 

if you're happy with the mechanical performance, then start on brakes and suspension.

 

The brakes have work done to them too, but the suspension does not. I am looking into that and body work, but am curious to know what I can do for more power. I was thinking of turbo charging or super charging, but I don't know how much that would cost. Do you or anyone else have an idea of the cheapest way to go about doing that? And also, what other mechanical upgrades I can do for more power.

 

well, without any details of your setup it's hard to say anything truly insightful. i'd
suspect that you have some more power hidden in there, but it'll cost you to extract it. you could always go fuel injection and good engine management. that way you have a better chance of making more power without having to rob Peter to pay Paul to the same extent that you would if you kept the carbie. that's one way to go before forced induction.

perhaps play around with intake and exhaust configurations, but unless you can weld/fabricate, then that can get expensive quickly just as well.

then that leads to forced induction ...

first of all, get "cheap" out of you functioning vocabulary right now. next issue is of course, the lack of deatils again - compression? carbie? - you must tread these waters very carefully. nitrous is probably your least expensive option, but that's not to say you won't need to tune the thing as well because you will. both turbocharging and supercharging can be made to work with what you already have, but it's probably not the way i'd choose to do things.

hope some of my ramblings help a bit.