Right now I am running no muffler with a y-pipe in place and duals out the back. It is extremly loud but I want it a tad louder. The problem is I live in MA and we have emissions test annually. I was thinking of gutting all 4 cats and replacing them with 2 hi-flows. My two questions are will the 02 sesors be effected with the hi-flows? And, do you think I will pass with the hi-flows and no muffler?

 

 

I have true duals on mine with two high flow cats and the truck runs fine and passes emissons. i have mufflers too but that wont effect the emissions testing and it will be louder.

 

High flows wont affect the O2s.