Do it! You'll love it! It's the best accessory that I've added to my truck. I really like the ECM control which allows you to shift gears without the exhaust brake engaging. I also added a shifter mounted switch which allows me to turn it off when going into a tight turn on wet roads or when I'm stopped at traffic lights.
Only question that I would have for you is will it adapt to your 4" exhaust? Have you retained your stock elbow off of the turbo?