What computer code works best for my 02 zx2 with a manual trans? Thanks in advance for the input.
NGP0, they’re rare(from 99 sr)
CWQ3 and XHG3 are good also, but rare(from 00 sr)
LXQ1 is supposedly better than anything but NGP0, but I’ve yet to see proof of it, it’s a regular 01 mtx code
If you are seriously looking to replace your stocker ecu… A s/r ecu is a good improvment also lxq1 (like stated above) you could also get a blue superchip, that will pretty much turn your stock ecu into around the same as a s/r ecu. If you really want your moneys worth I would go SCT!!! Sct is way worth it!!! The base tune they use is supposably NGPO… Then you can tweak it to your specs!!! I know a good place to order a sct. Also if you go the blue superchip route… Say you find a cheap chip on ebay and its programmed for a different ecu, i know a place that will reflash the chips for $40 vs. Superxhips wants $125+shipping!! If you are interested in more info on these places pm me 
I did get a SCT. It is a great purchase. You can tweat some things, but only to a certain degree (so you don’t blow up your engine).
If that’s not enough control over you engine’s computer, you can purchase the Ford Advantage III to use in conjunction with your SCT.
If you are looking for more power out of the box. It’s a great buy.