I couldn't quite figure out how to enable the no sound bug, so I created a test WIP with the BGM and sound FX left intact.
As stated in the rejection message, I was able to
beat the first race time by 179 frames due to purchasing a performance upgrade for the starter bike, in the very beginning. Taking into account the lag frames spent by entering the shop menu, around an additional 440+ frames can each be theoretically saved on the next three races (since Lars' run didn't purchase any upgrades until race 5).
Along with RAM address 09C4, strict adherence to ensuring maximum speed is maintained could save even more time on each subsequent race in the game.
edit: Also Lars, I wanted to add that you did have some entertaining moments in that run (crashing your bike and flying through the air across the finish got a laugh out of me!). I am imploring you though, to allow yourself significantly more time to polish and optimize these runs.