RE: Rosie 45 vs 61
Remember though that the ultra thrust mufflers must be propped accordingly. Which may not always be optimum for a sport aircraft. You need to get the RPM into the range that the pipe is tuned for. I would not bother with a quarter wave pipe on a Super Sportster.
Now if you want to go pretty fast, easy and cheap, pick up a Viper and put the rossi .45 on it.