BBK Throttle Body

BBK TB installed, IAC making noise

Just installed a BBK Throttle Body and Densecharger to throttle body on a 99 Cobra. Now there's an air blowing or sucking sound coming from the IAC valve. I also notice that the back of the IAC doesn't have a hose on it like the 99GT has, it's capped. This is where the sound is coming from, I can put my fingers on the cap and hear the change in sound. Any suggestions? Is this normal?

Thanks

should air be escaping from the back of the IAC? Why does the cobra have a cap on the back of the IAC rather than a hose returning air back to the intake like on the GT?