I would recommend going with insulation, better to do it now than wish you had done it later. If you do decide not to insulate, I would at least do the shared wall with the house to cut down on noise in the house when your working in the garage.
Great transformation on the garage, well done!I was just browsing Craigslist before heading over here to GJ, was that your Mustang that i saw on there? Always had a weakness for a Foxbody.
I would either go this route or or if you planning on taping and mudding, just fill in the gap with small strips of drywall, the tape and mud will cover it.
Just wanted to say hey to everyone on the board. Been lurking for some awhile, and figured it was time. Lots of incredible builds on here. See you on the forums.