WGB

Just finished up an IB sub install on my 3rd gen Max.Sounds great,and goes really deep,using two twelves.Sealed off every nook and cranny,including each end of the package tray vents with expanding foam.

Then,I dug up some old threads on IB subs,and someone stated that sealing these vents is a no-no.

What's the deal here? Will I blow the rear backlite out if I roll the windows down at 70mph,or what?

Thanks