Just fyi, the exhaust brake should stay on all the way down to 1100 RPM. On occasion, mine takes a minute to come on when I'm using the high idle to warm it up in the morning. It seems to come on quicker if it's colder outside though.
About the only surprise mine has given me is on wet pavement with the tow haul mode on running empty. With a light tap of the brakes coming into a corner, I've had it try to break the rear tires loose more than once as it downshifted. A minor adjustment on my part fixed that. On dry pavement and in tow/haul it reels it in rather quickly. Not to mention it's fun seeing people look around wondering where the noise is coming from. I've startled more than one driver in traffic with it.
JB

 

It may be different for the Auto's vs. the Manual trans. I have broken my tires loose plenty of times on dry pavement, it is impossible to keep traction when it is wet, unless I skip shift.

 

I've have mine chirp the tires on occasion on dry pavement when it downshifts, too. The Michelins they put on them from the factory leave a bit to be desired. It doesn't take much to make them go up in smoke either.

 

I love mine so far...

 

SO far so good outa mine lot of fun when jackin with people too

 

I love it so far, 25,000 miles and no problems and the noise it makes is awesome.