The RV had the wrong mufflers installed. So I was sick of the RV sounding like a Harley or a GTO, so I installed the proper mufflers and it clearly smoothed out the noise. However it’s still not where I’d like it to be. The problem is the pipes from the exhaust manifold to the mufflers are to short. In addition there is limited space to run them further. I could have fabricated and bent the pipes but I would change the clearance (height) from street level to the under-carriage and I need that room to the RV up and down to the campsite (incline and uneven terrain).