Ok, so a 30 minute job turned into a 2 1/2 hour ordeal. It took me almost 20 minutes to maneuver the filter into position inside the housing. (FYI...there is no top lid for the filter housing. If you want to change the filter you have to remove the housing, but the PowerCore filter is supposed to be good for up to 4 years or 100,000 miles.) Then I realized the filter housing wasn't sitting flush against the fender. It was stuck on a bolt that is welded to the fender as a ground post for the HID system. I had to cut about a 1/2" off the bolt to get the clearance needed. Then I had to free up some slack on the wiring harness for the air temp sensor. Needless to say, I was very frustrated by the end.
I added heat reflective tape to the back side of the housing to reduce the heat from the coolant reservoir. I also added some weatherstripping for better seals against the engine compartment. It was too dark for pics when I was done, so I will post the finished product tomorrow.
On the plus side, I can feel a noticeable improvement in throttle response. There is an increase in volume at WOT, but nothing noticeable at idle. No audible whistle. Next time I make a decent trip I will monitor the mileage and report what I get.