Based on your "lightly used" comment I'm going to make a few assumptions...
1) The bike had +/- 1000 miles on it when you bought it
2) since the bike had "custom straight pipes" the haimhead that had it before you had absolutely no idea what he was doing when he put them on.
3) I think I remember that it still has the stock air filter so refer to haimhead comment above
This is not a Harley. Rockets don't make noise to no avail. If you try to treat them like a Harley, as the previous owner obviously did, you get what you have now...a bike that is ill mannered. My advice to you is to take a deep breath and begin again. Either ask nicely among the folk here who probably have stock exhaust systems sitting around collecting dust and probably near free or do you homework, improve your air intake, buy a proper exhaust and enjoy a beast with ~ 160 hp at the rear wheel.
You have in your possesion a machine like no other. Treat it as such and you will never quit smiling. Treat it like a Harley and you will forever be chasing performance gremlins. Just my $0.02