An Irish golf journalist covered this on The Cut this week. The Irish pronunciation is Mac dool, the British version is Mac Dowell. MacDowell has said he is fine with either, it doesn't bother him. As people have been using Mac Dowell for so long he would look a bit of a prima donna if he stamped his foot now. If it bothered him you would have thought he would have corrected it 20yrs ago.I do wonder why McDowell hasn’t taken the time to correct the commentators from both sides of the pond who continue to wrong. I know it may not be how it’s said in England, but the joy of names is that the person themselves gets to decide!
Whatever the pronunciation it has to be better than G-Mac, that is plain embarrassing.
(I've given the Irish pronunciation for everyone else's benefit, not yours. I've never heard it spoken that way before the interview I mentioned on the podcast)