Jul 18, 2013 · Stick close to the factory pipe diameter. A 2″ dual exhaust system has enough capacity for a 300 hp system. Adding 1/4 of an inch to each pipe adds capacity for nearly 400hp. Going any bigger than 2 1/4 inch pipe diameter is usually overkill (and will often cause your engine to lose power).. Also, have a check engine light and what appears to be a DEF light. Truck has 2780 miles. Thanks in advance. ... Only reason I got the service message was the hose came off and couldn't spray the fluid into exhaust Sent from my SM-A705U using Tapatalk. ... Service def warning is an indication that something is wrong with the system. Heater. "/>Exh system light truck