ORIGINAL: Pat Roy
My experiences have shown the J&A to be one of the best if they alreay have one available for your engine type. I have not yet tried a J-tec so it's definately worth looking into. For quiet with a performance benefit you need to step up to a short cannister type. From there you end up at tuned systems.
I currently have a Cap with a DL-50 with stock "muffler" on it. My friend flies a Yak witha DL on it as well, but has the new Jtec wrap around on it. While it is slightly quieter, it is stil quite loud.