This goes way back, but I did the foil delete, then I did the hood insulation delete to hear even more whistle. It was ok, but I wanted more. So, when I put on my ATS housing to fix my turbo surge, I went ahead and did a WW just for the sound. Holy 5h1t!
It was so loud this way. The whistle was driving me nuts on the highway. It sounded great when it was spooling, but then it was too much. I was ready to take the WW out, when I remembered the hood insulation.
I put it back in and now I love it again. It is the perfect amount of whistle now. I didn't think that piece of cardboard made THAT much of a diff., but boy it does.
The reson i'm posting this is for the guys out there that just can't get enough whistle in the cab. If you have done the foil delete and a WW, then you should try removing this from the hood. It literally takes less than 5 minutes to do, and it's free, and it's easily reversible in 5 minutes.
You'll either love it and be glad you did it, or you'll have to put it back right away.
Let me know if anyone else has had the same experience with it...