Any way to strengthen transmission besides flash?

My e90 335i production date is 09/06 so im out of luck with getting the transmission flash to help with firmer shifts...i want to really add some mods, maybe fbo only for now, but was curious if there is any other way to strengthen my transmission to support the added power besides getting the obvious like larger tranny cooler or more frequent trans fluid changes. Has anyone tried a valve body upgrade to create firmer shifts? I really dont want to begin moding and then have my transmission begin to slip...thanks im advance

Btw i have 106k miles on complete stock car right now