I've been dealing with a 1st-2nd gear change grinding issue when shifting hard. I've read that changing to stiffer mounts will help with this particular issue. I would be more than happy to do a review for TiC on these mounts.
I have a 2011 STI hatchback with about 15k on the clock. I'm running Cobb stage 2 + SF intake 91 oct map, Cobb SF intake with the cold air box, catless Invidia divorced WG downpipe, and GReddy Spectrum Elite catback. I also have a Cobb adjustable short throw shifter and Katboy front and rear shifter bushings (grinding issue became more apparent after this). I recently installed Stop Tech braided stainless steel brake lines, Grimmspeed brake master cylinder brace, Goodridge braided stainless steel clutch line (install instructions and review below), and flushed both systems with DOT 4 brake fluid. Other than cosmetic enhancements, that's about all I have for performance mods.
My car is a daily driver that I also use for track and autocross events. Here's a vid from a few months ago:
This video is the best example I can give to explain my 1-2 grinding problem. Sorry for the long intro, FF to 1:15. You can clearly hear it grind when I shift from first to second gear:
I did an install writeup on my clutch line, mainly because I couldn't find one really anywhere. I have lots of pics and went into as much detail as I could.
I also have a sound clip of my exhaust setup.