They are usually warranted for the life of the product based on the recommended replacement intervals by that manufacturer. It shouldn't be any different to the fitting of the same belt with the additional VAG part number added. That said, it's usually only the belt that is warranted once correct fitments and no contributory factors to the failure are identified. This is where you find out the integrity of your garage!So these no oe parts what parts warranty do you get on these just asking ? No great mark up on these either if you go to TPS for instance, in regards to air, fuel , dsg, and pollen filters do you know if the particulate size is the same a genuine as my time in a dealer and experience is you’ll be handed a much higher bill if a tech sees pattern parts and comes to do a repair, cheapest can be the most expensive in the long run, in reality pattern parts are not really cheaper these days, i had a customer wanting shocks doing the other day and they wanted to supply their own bits from a supplier and they were £30 more for unknown brand compared to genuine
Ref filters, I use either Mahle or Mann (preferably Mahle) as those are the ones used by VAG in the initial build although they are very basic for our engines - no worry about thread quality, non return valve or by-pass valve placement etc on our oil filters.
I'm not suggesting for a second to skimp on the quality of the parts used and happily spend more money on premium brand oil and service parts instead of shiney side steps and spoilers. I used to work for an automotive OEM and actually approved suppliers' manufacturing processes for the parts they were going to supply to my employer - the supply base included both Gates and Dayco. I'm very particular on filters, especially fuel filters and will happily pay double the price of a Blue print, Wix, Comline, Fram etc to get a Mahle.
If you can get VAG parts for the same price as the Gates, Davco, SKF, Mahle etc parts then great. I'm sure your customers appreciate it.