Statement included with Kooks headers; "Kooks will not warranty any exhaust product that has been improperly installed, crashed, welded, or modified (coatings, header wraps, etc) in any way." All header manufacturer's say the same thing. Kooks offer limited lifetime warranty. Even the cheapest BBK headers offer 12 month warranty. I've never had an issue with headers that were ceramic coated from the factory. My BBK's look like new after 3 years. I did wrap some of the components that were near the header tubes but I will not wrap the headers for a fraction of a HP on a street machine. Never heard of a knock sensor pulling timing because of under hood heat, I thought they sent a voltage signal to the PCM based on a knock frequency.