I started out with a K&N, and after reading the posts here, bought the Scotty 2. I did do the cut out in the firewall, but it was just too loud. Anyway, I have been running the Scotty for over a year and have cleaned it frequently. I decided this past weekend to put back in the K&N since it was already cleaned and oiled. I also drilled 4 1-1/2" holes in the bottom of the box. Well, I got a surprise. I immediatly noticed that it was a little quieter, with no performance difference. What else I noticed was that it seemd to cool down quicker! I have watched very closely, and even with the nice 80+ degree days this past week here in So. Cal. it still cools down a little quicker on the same drives! Kinda interesting.....

 

That is interesting. When I was running the stock turbo with the scotty it would cool off instantly. Now with the KSB-1 it takes significantly longer. I blame it on the turbo, not the scotty. I do know that when I closed off the hole for the scotty my cruising temps went up about 100* compared to when it was opened. I need to open the scotty and see what it'll do.

 

Best of both worlds, run a 3" clothes dryer vent tube from the stock air box to the hole you already have in your firewall. You'll have to plug the new holes you made in the bottom of the airbox, leave the stock hole open though.
I have a Scotty on my 3500 and the setup below on my 2500, they both work about the same except one was a couple hundred bucks cheaper. It will be just as loud as a Scotty in the cab though.