Bavauto is legit. I purchased my remus exhaust from them since they had the best price. I've used them on and off for bimmer parts over the last 5 years.
2009 AW 535i
-Sport, Premium Package, and Comfort Access
-20" Forgestar F14 Black Gloss, Cobb PTF E30 map, KW V2 CO's, Remus Sport Exhaust, BMS DCI, RPI Scoop, Full Front 3M PPF, 35% tint all-around, Orion V4's, Bruce v6.1L cables, LED interior lights, WeissLicht License Plate LED, Trinity Smoked LED side markers, Bimmian Smoked Reflectors, OEM black gloss grills, and Invisibulb turn bulbs.