Not quite, I got a -40. ;-) That's the best I know for sure you can do, but it might be possible to hole-in-one #11 or hole-in-two #8. I'm pretty sure you can't go beyond -42 though.
Really loved this game and the soundtrack, btw. I'll be checking in later to see if it becomes a complete game.
One bug is that typing 'm' on the high score screen will toggle the mute. There's also a glitch where sometimes you putt backwards, but I haven't been able to figure out what triggers it.
Update: I succeeded on getting a hole-in-one on #11, a hole-in-two on #8, and one more improvement. So -43 is theoretically possible. If you consider adding more features I think an expert mode with harder pars would be fun, since it's very easy to hit par currently. I'd suggest 1,2,2,2,1,4,2,3,2,1,3,2,2,2,3,2,1,3, or 38 total strokes, or -34 under the current par. It's possible to get under that par for at least 8 holes.