I am 4000 miles in with the Dinan exhaust and the droning has decreased slightly but still noticeable. I am also interested in how long it took before it goes away.
14 Porsche Boxster S - http://www.porsche-code.com/PED27M31
12 BMW 550i xDrive (Dinan S5, Intercoolers, Exhaust, Springs/Shockware, Negative Camber/Low Compliance Arms & Intake; 3M CR40; AG M355, Michelin PSS & Tikore Ti Lugs) - Alpine White, Beige, M Sport, Cold Weather, Premium Sound, ARS, Sport Auto, Power Shades, Side/Top Cameras, HUD & BMW Apps.
13 Infiniti JX35 AWD - Fully Loaded
07 BMW 550i - Dinan S2 & CF Intake (Gone)
09 Hyundai Genesis 4.6 (Gone)