The warranty issue would be a concern. Normally, in my experience, if one replaces a part of our car, only that part is taken out of warranty. I have an older Jeep GC. I bought it with a non-mileage limited warranty (not transferable and no longer offered). I added the "Old Man Emu" lift and suspension mod and was concerned as to how it might affect the warranty. I was told it would do so only for the replaced parts. And in fact, in the years since (I now have 170,000 miles on the Jeep and the warranty has saved my around $15,000!), it has not been an issue. Still, on a car as expensive as the Tesla S, I would not want to take any chances. I might be more comfortable getting a mod from Unplugged Performance given their relationship with Tesla (though I don't believe they offer a steering wheel currently).