I just upgraded my reed block to a v force 1,it did make a difference on lo end havent been able to open it up tho.I wonder if I was suppose to put the old reed stuffer or its a piece of plastic shaped like a V that went into the cage between the carb an the cage it actually sat in the cage.not sure if I need this piece with the new reed system?I tell ya this 400 is a son of a gun,w the pipe,flat slide carb an reeds holy smokes this thing gets up an gets to the fire.lol polaris shoulda tanked the 500 an kept the 2 stroke.All this power an speed an now it really dont turn worth alick a fire truck turns better then this thing.haha