It took me 30 seconds after driving into my garage for the first time, ok it was just changing the antenna to a stubby, but a mod is a mod.
Tomorrow, Alarm, modules for the windows (all auto up/down + closing when armed), remote start, tinting the rest of the windows. The rest of the mods will follow as I find out what I want to upgrade/custom. After a week, I already know I want to repad the centre console.
As far as mods/warranty work, they have to prove the connection. I've been lucky with my Nissan dealer, plenty of mods on my xterra, from tires, aircharger, suspension and dealer has yet to bat an eye on coverage.