Hi fvl,
The way things have been going across the counrty with so many Predators being sensitive to jetting/pipe changes, if I had it to do over, I would just wait a while and see how some of the new complete and slip-on systems test out.
HMF, PowerTech, Polaris (White Brothers), Yoshimure, Trinity, and FMF all currently have or are working on systems. I really feel y0ou should wait for jst a few weeks to a month,,,I think they'll all be available by then...
JJ