Daily driver Altima, thinking of some DIY work for gas mileage. Suggestions?

[MDoe8]

I've got a 96 altima for my daily driver. I'm about to take the timing chain guides off as they are finally getting to annoy me. I was wondering if anyone has any experience with the altimas heads and intake manifold? ?I was thinking about taking them off and porting them out to get a bit better gas mileage. If they are already pretty well made, then there is no point. I'm just trying to scavenge as much as I can. I've already got it to roughly 25-26 city but I feel I can do better. Thanks

-=Mike