I agree, the D16Z6 SOHC VTEC would probably be the strongest D-series engine your going to find. A ZC might bolt on, but while they are DOHC, they're still 1.6L and they don't have VTEC. They're also pre-OBD which will cause wiring headaches. I'd consider either doing a D16Z6 swap and convert the tranny to a manual or just dump that car and find a 5-speed EX (or I guess Si if your in Canada) that you like. Save yourself a lot of work and headaches to get to the same point.