so ive been sitting on this for a while but finally pulled the trigger on the mars/cap mod for my IC-7300 last weekend. pretty straightforward honestly, just the one jumper on the main board, took maybe 20 minutes including the time i spent second guessing myself and staring at the board with a flashlight.

what i actually wanted to talk about though is the audio filter mods because thats where things got interesting. been running the default TX audio for like two years and just kind of accepted that it sounded whatever it sounded like. buddy of mine on 40m kept telling me my audio was a little boxy sounding and i kind of brushed it off. finally swapped in the mod for the bass rolloff and tweaked the mic EQ settings in the menu and man the difference on the waterfall alone is pretty noticeable. reports have been way better.

anyone else gone down this rabbit hole with the 7300? curious if theres other mods worth doing that im not thinking about. i know theres the fan noise thing too but mine doesnt seem that bad so maybe ill leave it alone for now.

yeah the fan mod is only really worth it if you run high duty cycle modes like FT8 for long stretches, otherwise youre right it prob isnt worth opening it back up. the audio stuff you mentioned is legit though. i did similar adjustments on mine and combined with a decent compressor setting it really cleaned things up on SSB. what mic are you running? i found the stock hand mic was kind of fighting against any EQ i tried to do, switched to an SM58 with the right impedence matching and suddenly everything just sat better in the passband. the 7300 is super tweakable if you know where to look in the menus, half the stuff icom buried in there doesnt even get mentioned in the manual properly.

I did the MARS mod on mine about a year ago, no issues. One thing I'll throw out there — if you ever feel like going deeper, there's a handful of guys on one of the SDR forums who've done work on the RF board to squeeze a bit more clean output on certain bands but honestly that starts getting into territory where you can really mess something up if you're not careful with a soldering iron. I bricked a perfectly good HT once doing something way simpler than that so I tend to respect my limits these days. The menu-level stuff and the jumper mods are pretty low risk though, sounds like you did it right.