This is the one
For starters, I ride a HD '99 FLHTCUI Ultra Classic. Prior to purchasing Cobra, I was running a 2 into 2 powerport system and using ThunderHeader pipes (which by the way I will never get rid of). I went with an all Cobra system using True Dual header (part 4400248), along with 4" pipes (part 4402396), and fuel modulator (part 202474).
If it's not loud, I'm not proud! However, long trips with the ThunderHeader pipes had me arriving places deaf for 20 mins. Windows would rattle, cars would swerve, and I'd be smiling all the way to work, a 45 mile stretch each way.
These pipes offer a great compromise to the always fantastically loud Thunders. A solid and subtle, yet distinct rumble, when parked & idled. However, if you wish to be heard before seen (and with an exhaust note you can be proud of), simply twist the throttle. The sound is incredibly refined and baritone in addition to offering a crisp hammering exhaust note that is unmistakeably Harley.
Obviously, for me sound is important, but so are other factors:
Looks: Good luck finding something better looking.
Performance: Concerned with going true-dual because I was told performance would be seriously hindered. Not sure if this is incorrect, or if it was offset by the simultaneous installation of the fuel modulator, but the torque actually feels strengthened.
Installation: All do-it-yourself personnel should find it very do-able in about 3.5 hours. That includes removal of the old and installation of the new to include headers, pipes, heat shields, and in my case, fuel modulator.
In summary, I'd do the exact same purchase again, and I'd do it with Dennis Kirk. No one came even close to the deal and all parts were in hand within a matter of days.