I have a 98 3500 dually with the V10, and it currently has a true dual exhaust system (2 sets of pipes all the way back, 2 converters, 2 mufflers). The problem that i can see is that for one, it is rusted and needs replaced. 2nd the tail pipes are 2" and look dinky sticking out the back of such a big truck. I have talked to a few shops around town here and they all seem to have the same idea. Get a muffler that has 2 inlets, and 1 3" outlet.

The current dual system is 2.25" then goes down to 2" after the mufflers - I talked to the people at Flowmaster, and purchased a 70 Series Big Block II muffler. This has 2 - 2.25" inlets, and 1 3" outlet, then I will run the 3" all the way back and dump out behind the passengers set of dual wheels.

My question is - Has anyone out there experienced exhause work on this type of vehicle, and if so what kind of system, performance, MPG did you see.

Please let me know.

 

Can't tell you what type of performance or MPG you'll see, but it will probably be much better than your old system.

Though I would've went for 2.5" in and 4" out myself. Make sure you don't put the muffler too close to the motor as well. It shouldn't be any closer than the beginning of the box.

 

got the muffler put on and drove to our camp that is about 100 miles away - got about 12-15 mpg. The sound from the Flowmaster is nice, not too loud, but has a nice rumble (Keep the neighbors happy) I did notice a little more bottom end performance. The new tailpipe looks so much better.