Now there’s even more to love about Heidi Montag, star of the MTV reality show The Hills.

Montag, 20, underwent breast augmentation surgery on Monday at the Beverly Hills office of plastic surgeon Dr. Frank Ryan.

Sources say that Montag had been considering the procedure for several years and just recently decided to go under the knife.

Montag, an aspiring singer who is recording a pop album with record producer David Foster for release later this year, waited to have the procedure done until after The Hills’ second season wrapped.

The show’s finale, which aired on Monday night, showed Montag moving out of the apartment she shared with best friend Lauren Conrad to live with her boyfriend, Spencer Pratt.

“Heidi just doesn’t want to make a big deal out of it,” says a source. “She did this for herself, and she’s hoping to keep it as private as possible.”

Montag, whom we’ve learned is recovering well, couldn’t be reached for comment.