The Dunlops have won four of the six races so far at the Southern 100 meeting at Billown.
Michael added the postponed 600cc race to the Senior title he took last night and William won the 125 and 250 races.
Other class and race winners on the night on drying roads were Roy Richardson, Wayne Hamilton, and two for Ryan Farquhar.
In the sidecars, Manx passenger Dan Sayle continued his winning partnership with Austrian Klaus Klaffenbock - the pair won both three wheel events at last months T.T..
Dan was delighted to be a winner with Klaffi once again:-
Just one incident - Laxey rider Andy Cowin came off his bike at Stadium on the last lap of the final race - he was taken to Noble's Hospital by air ambulance as a precaution with what are described as minor injuries.
There's more racing on Thursday with roads closing at 9.50am until 12.15pm and then between 1 o'clock and 5.30pm at the latest.
And an added bonus - with the sitting of Tynwald now finished, you can listen to the day's racing at Billown on our AM1368 frequency.