You could go buy NSMB, I am pretty sure it has 4.1 update on it from what I have read from others. You would want the jap version of course. In the future you should either block updates with your chip, scrub the update off on your pc, or load games with updates using gecko os- it will block the system menu update but prompt to install any needed ios, very cool.
There is another way, but I won't say it yet as I don't know that it will work. But another person should be trying, not from my advise and if it works I will let you know, I would think it would but have not seen it posted so mouth closed. The only fix I have seen for you is to update to a higher system menu that is in your region from disk.