OK... first of all, you say you bought an Si with an H23 engine, but then you stated that the engine is an H22A1. Which is it?
H22 means that it is an H-series engine, and that it is a 2.2 Liter displacement. All H22 engines have a VTEC (not VTECH) head on them. If you currently have an H23, and want to swap to an H22, then yes... you will need to switch to the H22 ECU.
All other info as far as what you need for the swap is contained in the FAQ's that can be found on this site.
