Explosions of 1MT or above use the optimized version by default, and that can't be changed through settings. I get that this is for performance reasons, but not everyone's machine is the same, so it would be cool for those with higher end PCs to be able to process some of the bigger explosions to their fullest glory. My mid-range PC, for example, was able to handle the non-optimized (done through mod files)1MT detonation with some difficulty, but without crashing. A good solution I think would be to put a setting that says "optimize explosions for X tonnage and above", and the user decides what the minimum tonnage for optimization should be.