To upgrade to the Super T&T store, the player must spend a total of 25,000 Bells in T&T Mart and 10 days have passed since the opening of the store. The player must also have had the Gardening Store constructed in the Town, and have had it open for 10 days.
To upgrade to the T.I.Y. store, the player must spend 50,000 Bells and have had both the Gardening Store and had Super T&T open for 21 days each before the option to upgrade is made available.
Upgrading to this store will change the music that plays on the Main Street. Specifically, it adds the added second variant of the song before the original default Main Street song.