Even though we were building a custom trailer to pull behind the Miata we still wanted a little more trunk space. The MSM was the first M2 we had ever owned and we were a little disappointed in how small the trunk was compared to the M1. We never carry a spare in the Miata (there are always plenty of people around on a trip to Deals Gap or other events to borrow a spare from) so there wasn't much need for the "volcano" that remains in the trunk after the tire removal. After a surprisingly short discussion with my wife we decided to get out the spot weld drill bit, the pneumatic body saw and a small sledge hammer!

FWIW, it doesn't look very nice in the trunk now but the extra room is great to have. We are friends with the lady who makes custom luggage for Miatas and will eventually get a set designed just for the expanded trunk as well as some custom carpeting for the trunk floor. When we finish the trunk will look "stock".

The tire mounting bracket on top of the volcano would need to be removed:



Also, the bracket that holds the scissor jack would need to come out as well:



I used a drill bit to remove the spot welds:



The regular drill bit left holes that were a little too big so I used a cheap spot weld drill bit I bought at Northern Tool to remove the scissor jack mounting bracket:



After drilling the lower spot welds out I used the body saw to cut the rest of the bracket off:



A few blows with the sledge hammer and the volcano is no more. The pictures make it look easy but in reality I got carried away and sunk the floor of the trunk too far down. It was touching the muffler sheild and I knew I would have heat problems. I ended up pulling the muffler and using a floor jack to raise the floor back up. This added an extra hour or so to the project: