For any car including Audi Q7 timing belt is the most important part for gas grid. The accessory should have 83 teeth and be of 24 mm width. Company installed ordinary belts in 2008 and CASB engines proved their efficiency. Also look at profile type – it’s HTDA, gap division should be 9.525 N/mm. The size of it in Q7 engines with model code BUN is very important. When servicing Q7 3.0 buy original Audi timing belt – it’s not so expensive.
Always buy toothed belt for CCMA engine code with recommended width at 24 mm. Actually, there are plenty of analog parts for Audi Q7 with 4.1 engine. By installing other than HTDA type of profile belt you won’t get needed gap division of 9.525 N/mm. Check if your parts for service of 2006 Audi Q7 are of good quality.