I'm new to the message board, new to Dodge, and new to Diesel. Just bought a 1996 3500 Dually with the cummings. I will be doing alot oftowing with it (13,000 to 15,000 pounds). Have read alot about 4' exhaust systems from the turbo back. There supposed to increase power/torque and lower egt. Just wondering if anyone has any pointers on which system would be the best. What is the best muffler, is 5 or 6 inch worth the extra money over 4'. I would appreciate any help. Thanks.