You don’t get the “full warranty” when you DIY hvac installs. You also need to call a licensed hvac tech to charge your system if it doesn’t come precharged. Mini splits are easy and I would 1000% DIY. Big, attic mount blower units I would leave to the pros for so many reasons. That said my cousin installed a 21 SEER unit for $5k. I was quoted $35k for the same system (: