We haven't got a Multistrada, but we do have a Monster 1000 DS, which essenally shares the same engine.
We found that with the standard cans the bike would have a severe vibration at around 4K revs, worse on the overrun coming down to a roundabout etc.
This has been totally cured by just fitting a pair of open silencers. Totally amazing. The transformation in the engine is like nothing we've experienced before with 'opening-up' a Ducati.
Cheers.
Lee.
http://www.monstershop-ducati.co.uk