FYI, did another test on Friday.
i figured i should try all the possible combo's with my setup to find the sweet spot, and reduce the drone with out any parts.
So here is my conclusion.
-Stock center resonator (x-pipe) with my vibrant muffler = drone from 1300-2000rpm. But sound great.
- My X-pipe with with my vibrant muffler = same drone as above. from 1300-2000rpm. But sound even beter then with the stock center resonator.
-My x-pipe with factory mufflers = no drone, a bit of sound, but needs a bit more for my taste.
So to reduce drone, i will need to tap in to the line and add a resonance chamber. Like Active Autowerk does on the E9X M3 exhaust system.
Or maybe i will try this muffler from Dynomax. Looks interesting.