I have been running a MBRP muffler on my truck since I bought it. We have decided on the current trip we are on that it is just to loud pulling our 5th wheel. I want to stay with a higher flowing muffler but want less noise so I was thinking about a Donaldson or Nelson. I know they come in 40" and 51" and would assume the 51" would be the less noisy of the two. For those running them how are the noise levels and where is the best place to get one on the internet?

 

also interesting in high flow mufflers...what about the hushpower mufflers from flowmaster? they are loud?