the butterfly is opening and closing as it should, its got no air restrictions or exhaust restrictions (check sig) so im now thinking its the BBM

How do i go about checking if its operating properly.

i notice there is a solenoid at either end (open/close the runners?) should i be able to see them move when starting the car or reving it ?

will it hurt to take the vacuum hose out while the car is running? (to see if there is any pressure at the end of the hose)

At the front of the BBM you sould see a vacuum regulated diaphram lever. At idle you should have vacuum on the black hose on top. So start the car if there is vacuum, the switching lever should move too long runners.

When the engine is rev past 3800rpm the vacuum is cut off and the switching lever will go to the short runner position(same as when engine is off)

Cheers