I tried getting the V-8 rumble and replaced the stock with a high-end, 'efficient' muffler. Out side, the sound was just beautiful-- like our cabin cruiser when idling-- inside, though was torture at cruise. The mind-numbing, over-powering resonance/burble was strongest at exactly those RPMs which we use on the inter-states.I did a "Y" pipe replacing the stock muffler and left the factory tailpipe. The interior noise was unbearable. I tried adding a 3"x18" glasspack blank and the interior resonance was still so bad that you could not hold a civil conversation inside the cab. I reinstalled the factory muffler, less the resonator.