First off, I'm aware of all the mechanics of doing it and that it's not a necessarily sensible choice. My application is a naturally aspirated 1.6 with a standalone ecu, Randall intake, AFM free, feeding into a full FM 2.5 exhaust.

My question is to those who have done it or are intimately familiar with rebuilds, what modifications produced the best returns for the cost?

Examples:

Polish and port
Three angle grind
Deshroud
Supertech oversize valves
Etc, etc

I do plan on skimming at least .030.


And because lately I've been hanging out with the wrong crowd I might just go ITB to troll the Miata turbo kids I hang out with.

I look forward to your thoughtful responses. (No I'm not doing a 1.8 swap)