SCarGuy

The whole car is warrantied by the manufacturer outside of wear items. As such, any change you make to any part can void the warranty given by the manufacturer.

He's also looking out for his staff interests. No one wants to potentially chase a wiring issue down the road, where the customer installed their own whatever. Because Audi won't pay him for that, and you probably don't want to pay their actual hourly diag costs.

So, it all depends on you and your tolerance. I work for Audi. I have a few modded cars, once of which is still under warranty. I chose my mods based on the brand, and experience I've had in the past. At the same time, I have the ability to replace any part of my car, inside and out, myself, if Audi decided to void the warranty for any problem. I've had one tiny problem with the car (water pump had a minor leak, which caused a very very slow coolant loss over a period of months). But, this was a documented issue with the car (RS3), and as such, Audi honored the warranty without issue.