I have a 2001 HD Road King. What are the pros & cons on 2 into 1exhaust , compaired to True Dual Exhaust? Does it increase torque, horse power?? Experienced replies encouraged.

I have a 2005 Harley FXST softail standard with 88ci carburated engine, with Vance and Hines straightshots HS installed by Harley. I am wanting to put unbaffled Samson Groundpounders on it because I like the sound so much better. I am wanting to know if there are any pros out there who can tell me what if anything special I need to do to it first. I have heard lots of things about back pressure, reversion cones, torque cones, nothing at all, just slap them on. ect. ect.
I am needing help so I do it right. Any and all help would be greatly appreciated. Where I live nobody cares about the roar! Thanks in advance........

Harley Davidson Road King performance exhaust modifications. Was told a little about drilling a series of holes, size unknown, that will increase torque and increase sound level. I would like to wake up any drunks behind me.