So far two different dealers have told me I lose my warranty if I do aftermarket exhaust.

This sounds absurd to me, but wanting to know if there is any proof to the contrary?

I had assumed when dealers say this it is usually to sell you OEM parts for extra pocket money, but I don't want to go do something only to find out they were right.

Anyone got any *first hand* information?

I know that an aftermarket exhaust is not actually going to potentially lead to engine failure, but I don't want a potential loophole for the dealer to back out of approving a potential warranty claim.