I would definately not just disconnect it and move on! If a spark plug failed would you disconnect it and move on? <img src="/forums/images/graemlins/confused.gif" alt="" /> The plenum valves rotate at around 3000 rpm, allowing intake air to dive directly to the intake valves, taking the shortest route. Below this rpm, the intake air is pulled through the entire length of the intake plenum, boosting intake velocity and low rpm torque. If you unplug the diaphragm, the valves will always be in the position for low rpm operation, not allowing the enhanced breathing at high rpm.

The updated lower plenum costs about $275 as I recall and isn't all that hard to replace. I did mine along with a new timing belt and plugs/coils/wires in about three hours. Ran awesome when done, absolutely hauled ass. Why have the 3.5L unless you take advantage of that 3000-6000rpm breathing?

Besides, even if you unplug the damn thing, you're still going to have unfiltered air leaking into your intake!