"I expected high (standards) but not as high as he's delivered so far," Musiala told reporters after the win.
"It's even easier to play with him than I thought."
Harry Kane (30) scored three in the dominant display and now has 15 goals in 10 matches for Bayern since moving from Tottenham in the summer, while also chalking up five assists in that time.
Musiala said: "I feel very comfortable with Harry, he plays amazing passes."
"I can run in behind and he'll find me."
Musiala, who grew up in England but plays for Germany, said he hoped the chemistry between the two would improve "the more games we play".
Musiala said it was important Bayern "show a reaction" after their midweek elimination from the German Cup at the hands of third-division Saarbruecken.
Bayern captain Manuel Neuer lauded his striker, telling German TV: "That's his experience, he brought it with him to the Bundesliga from England and he shows us it week after week."
Dortmund came into the match unbeaten but now sit seven points behind leaders Bayer Leverkusen and five behind Bayern Munich, with just ten matches played this season.
Dortmund sporting director Sebastian Kehl congratulated Bayern on the "deserved victory", telling reporters the "ice-cold" Kane "had chances which he made the most of".
"His teammates put him in good positions," said Kehl, though he admitted "on a few occasions we made things easy for him."
