The Lvl 172 is max because the inventory can hold 2240 items. But the next upgrade costs 2255 items.
Suggestions:
-more inventory space
-item bank
-more enderchest space
-compressed Air essence
-costs will stay same till 172
Suggestions:
-more inventory space
-item bank
-more enderchest space
-compressed Air essence
-costs will stay same till 172