it would take one hell of a lot of water to warp drilled/slotted rotors, I ran mine for over 4 years through winters and at the dragstrip and on road courses.

He will have no problems with them unless they are of poor quality.

I have no idea why people on this site have to bash every single mod and be so paranoid and act like a persons car will explode of they do so much as change their floor mats.