Think about it, you are talking about bringing a 1.6 SOHC non-VTEC up to the level of a 1.6 DOHC VTEC by about 52 horsepower (flywheel)... That kind of power in a D-Series motor can really only be found through forced induction like a turbo or nitrous. Even if you did a massive rebuild from the block to the head with aftermarket parts for an all motor setup, you'd have to do some pretty intense compression changes and bullet-proofing to get over 50 hp. A header and a cam upgrade on your D16 will probably net you around 7-10 horses tops.