Inspired by legends like JBOT, I build this shorty airbox. It seems to rip, but is this .8L setup giving me the same benefits as a tube and larger bottle. 64cc, single Reed, 17.5mm carb all polini.
I sanded out the mouth of the bottle and hacked off the threading to give a better clamp surface. I ended up cracking the bottle and taping it closed.
It lost some revs with this setup, but has a little more torque down low per butt dyno.
It seems to rip and is slightly quieter than just running a UNI foam filter.
Early pic with an unnecessary hose on the carb.
I went this direction because the carb faces straight out. This is a little more tidy than a long bending hose, but it seems likely to get knocked off. The carb is mounted with a flexible connector, so I am not too worried about damage to the carb. (edited)