Maintenance first, then research.

Check out Honda Club, Philippines and join up. Lots of people there can help you with mods that work and mods that don't.

IMHO, a lightened flywheel isn't really worth the trouble. To get meaningful performance gains out of a lightened flywheel, you'd need to remove a lot of mass. The stock flywheel will not be reliable if you remove too much, and if you get an aftermarket flywheel, it's $$$ that you could better spend on something else.

There are many engine management options available for Hondas, like the Apex-i V-AFC, the E-Manage, the aforementioned Unichip, Hondata (though it's pricey) and Crome... engine tuning is a good idea because while other modifications gain you 5-10 hp in one spot while subtracting it from another (intake, headers and exhaust work by moving your engine's effective power band up and down the rpm range), engine management will increase power everywhere.

Keep it simple. Learn about your car, do some simple breathing mods, then decide whether you want to go further with the D15, swap to a B16 ($$$), Turbo ($$) or simply go for engine management.