We have friends visiting soon and they want to stay a few days longer than 30 days. Does anyone have recent experience in extending a tourist visa while already in China (Kunming)?

Although the headquarters building of the Public Security Bureau is at 399 Beijing Lu, they do not service visa extensions.
The building which deals with visa and passport issues for foreigners is at 118 Tuodong.
From Beijing Lu, go east on Tuodong, about a 10 minute walk.
The office is on the 3rd floor, and the staff are friendly and speak the various languages..
Good luck..

Thanks so much!

You are welcome..