From what's been posted here so far, it would seem rmm, underhood bushings, shift "adapter" (plate?) at the trans, and trans fluid are the front runners for POTENTIALLY helping to achieve more positive shifting and gear engagement. Again, I'm not considering throw distance for this topic. The only thing autocross legal is the fluid change, so I will be looking into that shortly.
Again, what's got me asking this is that it seems almost impossible to have a consistent feel to the shifter. Landing in the appropriate gear sometimes seems like a bit of an adventure. Sure, I find the gear, but the location and effort needed seem just a bit variable. The rev hang is a huge impediment. And more than once now I've been almost locked out shifting to third from second when trying to be somewhat rapid and in the 4000-4500 rpm range in second going to third. I would like to find a solution to that as the way I do it is very natural to me. And this is at least my eighth manual transmission vehicle. So I don't think it's me. Thankfully, where I autocross, it's usually a single shift from 1st to 2nd and that's it.
Thanks for the input, and if anyone has something to add or has an issue with what I've tried to summarize here, please post up!