Just because I didn't want to work anymore and our phones do more than they used to:
Went outside, started truck, waited about a minute. Fired up Decibel 10th app on my iphone 5. These are all "eyeball subjective" since the app doesn't record avg/peak over a period of time.
Inside truck door closed chest height
Avg 55db, peak 58db
Outside Truck 2 feet from grill back turned to wind
Avg 80db, peak 82db
20ft from truck
Too windy to get any type of accurate reading.
Truck off
Avg 38db, peak 41db
Now If I could find my old 5.9 to do the same non scientific test. I know it was louder but would be "fun" to compare with the same app.