This may sound stupid... but pull the air cleaner off and just confirm the operation on the manual choke (butterfly to lever position).

I only mention this because most new motorcycles come from the factory calibrated on the LEAN side and you mention a rich condition.

A vacuum leak will make it even more lean. The air induction has NO effect on the performance of the engine, unless it has a vacuum leak.

Its purpose is to continue the exhaust burn inside the exhaust pipe, hence the extra heat. It is an emission thing.