Wallet pain but no gain. For stock & light mods BMW's are pretty well engineered right out of the factory. Personally I would have to wonder what if anything they can add when the intakes are in a high pressure area to start with.
2014 BMW 435M-Sport MPPK/MPE
2013 BMW 135is 6MT convt
2009 Ford Expedition 4X4 EL - 2009 V-Star
2003 Nissan Xterra 4X4 - 1998 Ford Ranger 4X4 Splash
FFR Cobra Mk-IV
work in progress
Very, Very Long List