It is not a bad idea to discuss modifications with the SVT Technician at your dealer or at other dealers before you modify. Then you can decide how far you want to go, and what will be acceptable to the dealer. There is only one SVT Technician at my dealer, and he is the only one that touches the SVTs. I was discussing a regular service issue with my Technician and switched to the big what if questions. My Technician does not look for mods during regular service. More specifically, he does not look in the cage to see the size of the pulley, or at the SC belt to see what size, or at the computer to see if it has been tampered with, or at the HE to see how big it is. 50 state legal exhaust is acceptable, and aftermarket intakes are OK (unless a recharged filter causes a problem). If there were a major service issue, then Ford would be looking for a cause (get it back to stock). After talking to him, I was comfortable with the mods I was considering, and know what is acceptable in case of a major failure. It was nice to be able to make informed decisions about my mods, and I am not loosing any more sleep over my warranty.