Yeah, put it through the extra hole. Make sure you loc-tite the bolt and nut. I just lost my muffler on a cruise yesterday, dented and scratched it up a little. Good thing I carry pliers in my backpack so i was able to bend the receiving end of the muffler back so it would fit on the pipe again. Also, I know I didn't leave it loose.
I never used the pipe on the stock setup (PA50 I, 20mph). Over the winter, I put a 70cc Athena kit, variator plate and wieghts, 21mm phbg kit, performance reeds and ported the block. Tuned and dialed in (96 jet) , it does 49-50 (chase car). It will cruise 40 all day at about 1/3 throttle. Stock gears. Gets about 45 mpg give or take. Initial take off is a little weak. i kind of have to push off with my feet but it picks up after about 5 mph and really starts pulling at 20-45. I weigh 205 so if you don't exceed the bikes rated limits by 55 lbs, the take off probably wouldn't be an issue.
Overall, I am very pleased with the pipe. Its built solidly, it looks decent, and performs awesome for my driving needs. Get one.