I had a banks sidewinder kit that included the 4" exhaust on my 89 suburban. Granted it was a 6. 2 wich is nothing compared to the cummins, however it definately woke the truck up considerbly and the banks set up never let me down. I even upgraded to the 6. 5 motor using the same sidewinder kit and it was working flawlessly up until my Burban was stolen out of my driveway in Southern California. I hope who ever has it is taking care of it. 
