how much of a chore would it be to change my zxi engine for a klze? would i need to upgrade anything plus would it be worth it please excuse me for being thick hehehe

Seriously man, there is heaps of info out there on this
A chore it would be, I'm on klze engine no3 and each time i was cursing the car saying "never again" but still i do it....
And while you will have more power, it will not be at full potential until you get a ECU to drive it, which will cost probably as much as the klze itself to install and tune.
If your like me, take it in 2 stages, klze first, then save up and get an ecu. OR install an ecu from a klze mx6 or eunos 800, but that will require some splicing with the wiring loom to make it work, AND won't make you quite as much power as a standalone ecu......
But if you want to know, in my opinion, the best bang 4 buck mod? Coilovers or exhaust.
Coils drastically improve handling, and an exhaust sounds nice and probably gets you as much kick as a klze (without ecu)
What am I saying? Klze is an easy mod to do, and doesn't need much to work in a standard BA, but you will only get about 10-15hp until you install an ecu to unlock the last 15-20hp...... so up 2 u man