the best "performance" pipe for a bagger may be a 2 into 1.

Define your needs, moving a 900 pound bike around town and through twisties at 3500 rpm , or a 600 pound stripped down bike in a straight line at 6000 rpm

some pipes will enhance power in one range at the expense of the other, so it's up to you to decide what are your real world riding needs.

I use supertrapp supermegs on my stock ( no cat) headers. supermegs are a tunable pipe- I tune for torque when around town, re-tune for horsepower on extended hiway trips.

there have been a number of pipe vs pipe shoot outs over the years, many of which can be found on the web, nightrider.com has one in their bike tech section-- i like that one because rather than focus on a peak number at a specific rpm, they look at power gains ( or losses) where real bikes are used.

when comparing anything, the comparisons need be apples to apples, rather than pipe ( + intake, +tuning etc.) vs stock. just about any pipe and hi flow intake will show 7 to 10 horsepower increase over stock.

Mike