My friend has a spare 4afe cylinder head lying around. I might just try grooving the heads or the intake valve as suggested one of these days.

My goal is fuel efficiency naman and not power so I don't mind losing some HP so long as I use less fuel.

Sir niky which builder are you referring to about the grooved intake valves? I might just give it a try one of these days. If it doesn't work, salpak ko na lang yung lumang head hehehe. TIA