Modifications whilst retaining virgin ECU. Searched

I did a lot of searching, and either there isn’t anything like this, or I’m just that bad at it.

Regardless, I’ve been wondering what are some of the best ways to make not just our cars, but any Honda/Acura, faster while using a virgin, unmodified ECU.

Obviously weight savings, lightweight flywheel, etc.

Now I know that simple things like, I/H/E, can help them move out better on a stock ECU, but what else is there? Smoothing out the ports in the head and intake manifold? Cam timing, shaving the head slightly, or mild cams?

Now I know that getting your ECU chipped isn’t expensive, and I plan to do it anyway. But I was just curious as to what things you can do while retaining an un-chipped ECU.