I'm not sure about bikes, but this is what I've learned from cars (mainly Porsche, but most should go along the same line). When converting an NA mortor to a turbo motor, CFM requirement changes. I personally haven't seen a lot of throttle bodies be a major restriction...the most common overlooked item is the plenum. As displacement and boost increase, more air volume is needed in the plenum to feed the cylinders. If the plenum is adequate, then that should be fine. If it is still in the back of your mind, bore each one up a few millimeters. If running a low boost system, you wouldn't notice a difference. As for the taper, could be for smoothing out the airflow...less turbulence in the intake means a more complete charge to the cylinders. This is pertaining to cars, so don't hold me to this. I saw your post down on the list and had a little input.
