As with anything else, make sure you understand why a mod works before you try it.
SOGI is pretty much dead. I think that my email address is still subscribed. Haven't got anything from it in years. Places like this offer a more robust line of communication anyway.
Air flapper and temp sensor mods? Good for a few ponies, maybe, but nothing really worthwhile.
Intake and exhaust are really basic. Another few horse give or take.
In the end, yeah, it's NA. And it's an NA that's making decent power. Any real power gains are probably only going to come by increasing compression, increasing volumetric efficiency, and/or increasing revs.