In short, yes. Rip himself put one on at the Idaho Bomb Party this spring.
Please be aware the downpipe isn't four inches. It would be a heck of a tight fit, and I'm not sure the surrounding items would appreciate the heat being that close.
Old Smoky has it on his truck (the one Rip installed), and I can attest it sounds awesome.
I have a 3 inch straight pipe, and I found that the exhaust velocity keeps the soot off the trailer... blows it out far enough when pushing the truck hard that the trailer stayed clean even after nearly 2000 miles of towing.
The 4 inch so dramatically reduces the velocity that at speed, any smoke just streams straight back. That's good, from an airflow perspective.