I have not tried to measure the sound level of the HPR 19 system. There are too many variables and testing criteria to get repeatable and calibrated readings that really mean anything. You will get different numbers with the same bike in different locations and atmospheric condition when using expensive equipment and highly trained technicians.
What really matters is what number shows up on the cheap sound meter with a highly UNTRAINED park ranger.
What the park ranger sees on his meter even when he may have the meter on the wrong scale determines if you get to ride in his park. Keep your muffler freshly packed and don't be a jerk or try to be a know it all when he wants to test your bike. Don't ride irresponsibly so that they have reason to try to find a reason to put you and your bike in the trailer.
If you are showing you are trying to comply and your bike does not have that unmistakable never been repacked sound from the muffler they will probably let you ride.
If you have a silencer that is less than 3" in diameter, no matter how long the can is, it will not be close to passing anyone's sound test, even with a freshly packed muffler.
We make our silencers easy to repack by using bolts instead of the rivets. A silencer that is held together with rivets is time consuming and frustrating to get apart and repack. After the 1st repack the rivet holes will usually be loose and it is difficult to keep the silencer from falling apart.