I have auto and the single Borla exhaust and very minimal drone (stock 2nd cats INTACT still).
However, when I had the 2nd cats removed, it droned like a bitch and gave me headaches everytime I drove my car. I now have the stock 2nd cats placed back on and love the Borla exhaust now.
Like what Mr5 is saying, you will drone no matter with auto.
2008 E92 335i |Montego|GrayWalnut|Auto|ZPP|ZSP|Heated|CA|iPod|PDC
MODS: AeroLip|PaintedReflectors|PaintedKidneys|LowerBlk Mesh|EuroSwitch|AlumnPedals|M Footrest|KW V1|BorlaExhaust|4"Tips|35% F1Tint|6000Kd1S|BMC Filter|LUX H8|M-TechSides|V1 Hardwired|Vorsteiner CSL Trunk|CF wrap interior|EuroArmRest|M Tech Wheel|LCI taillights|19"BBS LM-R