I have never had this problem unitl I bought my new Shoei XR1100 helmet.

Basically the rubber seal around the bottom of the helmet at the rear sticks out a bit like a mini wing. What happens though is that it sometimes gets caught in a fold between my shoulder blades when tucking in thus locking my helmet to my jacket restricting my head movement. Even worse in my 2 piece suit with the jacket that is a bit bigger.
I thought that a new jacket with a back hump would be the fix as it would not be able to fold up between my shoulders. So after purchasing a Alpinestars Tech 1R today which fit perfect in store, and had no head movement restrictions decided to be even worse tonight.
As soon as I sat in the seat of the ZX10R the jacket shifted up my back and the hump pushed my helmet down facing the tank. It was even worse tucking in as the hump moved foward. This was still a problem with all 3 of my helmets (Ti-Tech, Arai & Shoei).
Does anyone else have this problem with back humps on jackets or am I just stuck in a shit position with my new Shoei helmet? I really like my new helmet and do not want to go modifying it to remove the rubber stickieoutie bit but also want to get a decent leather jacket that wont cause me dramas and restrict my head movement.