I've melted a hamburger bun sack to the lid. That was a pain to get off. still has a little spot on it. Other than that no mods really. I did make an elevated rack for the WSM out of a 18" grate and some SS bolts, and I use it more in the 22.5 kettle than the WSM. It is great for Roadside chicken or anything else that would benefit from the extra space between the coals and the food.
HALF DIAMOND RANCH BBQ
Home made 5' reverse flow smoker
Weber Kettle 22 1/2" silver series
Weber Copper Smokey Joe Gold 14.5"
GPS trackable RED super fast thermopen