Change coolant and use 50% green 50% deionized water (at any radiator shop) or the 50/50 premixed coolant. Will help from getting corroded up cooling system.
fill washer fluid to top
change engine oil then go
fill up add stabilizer let it run for 2-3 min.
pull in garage and put it on stands under the frame lifting the car as high as your stands will allow(helps keep air moving and moisture out from under it) suspension unloaded is always better.
get some fogging oil or chain waterproof chain lube and lube the shock pistons so they don't rust on you. If you have chrome or polished wheels spray them as well so they do not corrode / rust. You never know when a garage could get wet inside. door open in a rain storm, roof leak snow melting and running under door. so be prepared for that.
remove the battery completely and give it away,it will be bad in 3 years anyway and could leak and destroy you cables.
unhook wastegate and remove prom from ecm, just in case ... never know what goes on when your not home period !
That should do it and be fine. If your storage is subject to high moisture or it could turn to 4-5 years I would pull the plugs and put fogging oil in cylinders and button it back up. It could sit for 10 years that way.
write yourself a note and leave in on the seat of what you did before you left and a list of to do's before you drive it again.
Like chip settings ? did you have any changes made that reset with power off ?
Turn the boost way down or drain and refill gas. (easy to forget when your excited)