I assume your Integra ECU is a PG7. I have an 89 Integra PG7 in my CRX with my ZC engine. I wouldn't put back the SI PM6, because the Integra ECU has more aggressive timing and fuel maps. It will simply work better with the ZC engine. If anyhing, I would love to get my hands on PM7 ECU, which is actually made for the ZC engine, but they are expensive and rare. I was also told that if you chip the SI PM6 ECU, that PG7 will still work better. I'm not 100% sure about that.