Quattroworld.com is good for some topics - regional forums in particular are good
AudiWorld.com is better then Audizine for some models but less so for others. It also has an excellent forum spcifically for VCDS (also known as VagCom)
There are also some good sites for particular models - A50C.com is one such site specific to the B8 A5/S5/RS5 models.
E93 335i convertible, F15 X5 xDrive35i
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