The 98-92 360 TBI engine is much less tolerant of changes, it can not compensate as much as the MPI magnum engines. You may get some more airflow with a fresh air intake and headers/dual exhaust but it will not add more fuel to compensate and eventually you will start to get lean misses and surges... with any significant change. If you are gonna do any thing mabey throw some magnum ex manifolds on then a dual exhaust and cold air intake and a set of 1.6 roller rockers, that is about all the computer can hangle for changes. If you pull the heads it could probably stand a set of thin head gaskets or a little milling but thats it. Even all those changes are gonna net you very little cept mabey another MPG or two because they will lean out the mix. You may be able to step up the fuel preasure if you add a 93 style fuel pump and a regulator but you can't get crazy with that because more than just a couple pounds over stock and the injector will not work right. There is no one re-programming those computers any more (if ever)either. All told I bet you can't get more than 20 HP without stuff not working properly anymore.

If you are willing to do a carb you could make quite a bit more power very easily. Put on a t-quad on a stock intake, some headers, 1.6 rockers 340 valve springs, dual exhaust and you could easily get 50 more HP, a cam change, performer RPM intake and head milling along with the other mods and you could easily get 100 hp over stock.