I had the 4inch MBRP from the turbo out without the cat and muffler. This was great until I hauled a camper and the noise would bounce off of it and that got annoying real quick. I loved the sound but I could only take so much of it on a trip. I now have the MBRP muffler back on and I like it much better. Now my exhaust exits behind the rear tire and this may be different if it exits in front of the tire. I don't see how anyone could take it for long with duals straight out the back.
Scott
Hopefully I don't experience the same noise issue with the MBRP duals exiting from the sides. I can see how shooting straight back at the camper may be a problem --- every underpass in my area is a cause for a throttle-blip, but for an extended haul, this may irritate my co-pilot.
Aside: Last summer I ran into a fellow PowerStroker with straight duals. Every head in the campground turned to watch (and listen) to this rig pulling in. The noise wasn't offensive, but the turbo whistle was unreal under load. He was pulling up a slight incline with approx. 12,000 lbs elevating the trailer onto blocks - the whistle sounded like a jet spooling for take-off. He contended that interior noise wasn't offensive (wife and kids with him).
I will report in early spring on my setup.
