Personally I would go with the stock muffler. It is the lightest option, makes the most power and is most easily replaced. I had a set of Jtec mufflers once........just once. Yes it is also the loudest option however not by much. The solution to the noise is prop selection. On the 55 the PT 23x8 or the Falcon 23x9 will be fairly quiet. The goal is to keep the engine below 6,000 rpm. I currently run a 150 with canisters, very quiet at idle but very loud in the air, the culprit is the Bolly prop I am running, soon I will be trying a Mejzlik. I expect it to quiet down greatly.