Guys, I have a 3" straight flow exhaust setup on my turbo car. I have a mid-box resonator (pretty large one and is straight flow) and a pretty large straight flow rear muffler. But it's still loud and the droning at 2.6-3k rpm is killing me since I'm in that rev range a lot. I've been reading up about side-branch resonators and helmholtz resonators. It's those weird branch exhaust add-ons that apparently take away the droning by cancelling out certain frequencies depending on length of the resonator. Anyone tried this with positive results?