While I was trying to order a spare key for my new corvette I had an extensive conversation with the sales manager where I traded my XF. Basically, I was told that people turn away from cars that have been tampered with. Any modification you make that alters the looks of the car will probable not appeal to the masses and might even throw up a red flag as to say this car may be trouble. As beautiful as all your modifications may seem you will be better off to remove the mods before you sell it. Something as simple as a K&N air filter says performance is important and you probably have run the car harder than normal. Also, if you plan on trading your XF in on another car and your XF has been modified the sales manager is going to look harder at your car for signs of trouble. De badging is a definite NO NO. As resale values are somewhat low it doesn't take much to just wreck the value.