You've got a couple options to convert to OBD2, but tuning is not quite as simple on this platform as it is elsewhere. My BMW for example can be flashed with a cheap cable and companies like XHP and MHD offer plenty of off-the-shelf tunes. You'll find nothing like that on this platform. That said, on with the show:
If you just want logging, BlackStealth makes a MUT to OBD2 CANBUS convertor so you can plug it into your '92 and it will output OBD2 for logging with Torque on Android/iOS. It also accepts additional inputs for wideband/boost/etc. You can find it in the for sale section of these forums. With this, tuning is relegated to piggybacks but there's plenty of potential to be had.
For tuning and logging you can either swap to a Chrome ECU (sold at 3SX) for easy plug and play OBD2 logging and tuning, or get/make a harness to swap in a '99 ECU, and code it for similar functionality. I'd suggest Chrome personally as it will come pre-configured for your car and it's straight plug and play, but if you're willing to dabble in wiring and wait for deals the '99 retrofit will likely be cheaper. You'll be running Chrome in either case which opens up far more options than a simple piggyback such as launch control, ECU controlled boost, larger injector control (E85), and the additional built in safeties of the stock ECU.
You'll still need something to log important information, like EvoScan for PC or BlackStealth's convertor though, and you'll need a laptop PC and an Openport 2.0 cable to tune with ECUflash. Unless you're taking it to a dyno or street tuner, you'll be doing all the tuning yourself. The learning curve is a bit steep if you've never delved into it before, but all the information is readily available including a guide on our sister site 3SGTO from the maker of Chrome. Information from the Evo community is also relevant, and Merlin's Flash Guide has lots of good information.
Well, I think I've rambled enough; best of luck in whatever you choose.
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