Not for DIY'ers. The equipment alone to do system work correctly will set you back over $800.00. To make a freezer colder by that much you'd need a higher performing compressor for sure, and maybe a upgraded condensor, and evaporator as well. I don't know the details it's never come up in my residential business. Sealed system isn't something you can just do, and you're talking about expert level work. It takes a lot of practice just be get comfy. I'm guessing you'll need something you can rely on. So unless you're an HVAC guy accustomed to working on systems that small you'll have to cough up the cash to the refer superchager folks.