http://www.superflowmufflers.com/shopping.htm
I got those custom mufflers from these guys suggested by someone from here. the true dual I simply removed the crossover pipe and got a "J" mandrel bend pipe and created the bend and remounted the O2 sensor.
Those dyno run were performed by a local harley dealer. One thing I forgot to included, was the bike had been running on 87 octane for 300 hundred miles and during the dyno run. Yes it is a natural aspirated engine. The result were much higher with the Thunder Max with Autotune installed because of the Wide Band O2 sensor that came with the system. I removed it so I can focused on running with the stock computer since not everyone will spend 800+ on a computer. since it is Fall and the air is much colder I don't have hard data as to how cool the bike runs. Before it got cold it ran 16 degrees cooler, this is veirfied with the Thunder Heart digital multi function gauge I installed. It works great with the Thunder Max w/Auto tune.
One more thing, I still get the mid 40's mileage to high 40's. The system is dual function to run high HP and TQ in the city or for mileage on long runs. One thing I was impressed about the run was: The tech was cruising at 40mph on the dyno, don't know what gear he was on. but when he crank the throttle for accel test. from 40mph to 130pmh was 4.3 seconds.
My goal is to reach mid 50's and still maintain those hp and tq, thus far I am 3/4 there because of the mid to high 40's mileage. The other result that is hard to believed by my co-riders is how fast the bike red line which is fast throttle reponse.