Should have left the kart red (or repainted red) so that goofy red boat seat would at least match.
Seen too many boat & lawnmower seats on redneck go karts on craigslist.
So naturally I am biased, but I'm also a purist at heart.
The air filter doesn't filter the air. Dust goes right through it.
Ouch. Those filters are commonly used with a
foam pre-filter and sometimes with an outer mesh 'sock' as well. I've looked through those filters, they're very porous.
Yikes man, get a better filter and inspect the engine while you're at it.
Everyone wants the 'performance' cone filter sometimes just for the 'cool factor' but the stock air filter (box) assembly is actually quite adequate. They're really not as restrictive as you think and they will keep working effectively even if coated on the outside with dust, sand, wet mud, water/ice/snow, without sucking all that into the engine. Proper filtering is especially critical for the sand lot you're playing in. A continual diet of sand + dust with that lackluster filter is like adding a handful of it into the crankcase.
I've seen people around the web and on Youtube running the stock air filter assembly on karts that are faster than yours, so there's that.