So I put my MIT on my '05 1500 last night with the Amsoil drop in filter and I was surprised how quiet it all sounded. When I first got my truck, I put the Mopar CAI in it with the stock exhaust and man Hemi sounded like an old 440 when it was WOT. Of course, the EGR valve tick was driving me nutty and at the time the bypass mod hadn't come out yet and once I put my Borla exhaust on and was having resonance issues, I ended up going back to the factory air setup and sold the Mopar CAI. Of course, the resonance in the exhaust eventually died down and I wanted to do something in the CAI departmnet but had no desire to remove the air box again so in walks the MIT.

I figured just by the fact of taking the Hemi Hat off I'd have that same engine roar I did with the Mopar CAI but oddly enough I don't. It is a little louder and you can hear the air flowing more but nothing as dramatic as it was with the Mopar CAI. Is it due to the fact it's a plastic tube vice a metal tube, that I still use the factory air box instead of an exposed conical filter or am I just used to the rumble of my exhaust or is it all three?

I'm actually happy with how it sounds and the best part is as noted before in other threads, the EGR valve tick is non existant.

I recently added some extra length to my MIt with the Airaid universal kit. It added enough length to get a 9 inch filter into the fender space. I had a noticeable "tick" with just the MIT and a filter outside of the box.
As soon as I added the extra piece it stopped most of the tick. I think your right the plastic helps and then the length may also help.

Im running the same set up. it was too much noise at WOT with the airaid cone filter

Check this thread. Universal kit It shows pics of mine now.