It all depends really, if its well looked after and/or fairly std then it should pretty much run and run. Like all things though if it's been poorly maintained/poorly modded etc then it's difficult to say exactly.
The rb25 engine is a very popular upgrade, do a search on the forum and you should find all you need to know
The rb25 engine is a very popular upgrade, do a search on the forum and you should find all you need to know