It's got to be the cold start. This morning the wife was pulling the car out, I was behind it waiting - couldn't get in, too little room... the booming of near idle RPM coming out of that thing was deafening. I felt it through and through as well. So it must be tied to the cold start.
Is there a cheap/easy way to do it short of a $1000 tune? I have a Dinan tune on the car already, it came with the car, but still, would be a waste to overwrite it.