Manifold rubbers with & without restrictors

[roadrun_fr]

What is it ???????
VTR1000 Manifold Rubbers with & without restrictors :
http://www.dynobike.com/vtr1000_tips.htm

Does it make a difference to remove it ?
Do you think I will have to rejet the bike in case I have these restrictors and remove them ?

[roadrun_fr]

One theory here for the manifold intake :

I also read something in a tech column about Superhawks stalling under heavy braking or low idling. The deal is that since the carb throats are pretty big, under certain conditions, there isn't enough velocity to pull enough mixture from the carbs into the engine, and the bike stalls out. Honda fixed this in '99 by putting 5mm restrictor rings in the intake manifolds -- Peter has a '98, but apparently the '99 manifolds will fit the '98 bike, so I'm going to swap them in and see how it runs.

http://www.bluepoof.com/motorcycles/1202/121302.html