If you go to a reputable after market installer like hollandia ( i think thats their name) they will have a warranty and they do a good job too as some car companies contract the sunroofs to companies like this. I've seen an article in a mag where they install a sunroof and they don't damage the car at all, and they where cutting the hole out of a car with a custom big dollar paint job. They also put braces for the roof in too, so its not going to weaken your car otherwise they wouldn't be ADR approved.
