I am not sure we have the same EPA requirements as the US but I know our dealers are just as quick to void a warranty based on after market pipes, tuners etc. as your dealers.
Our dealer (fortunately who is a great dealer) will still warranty a bike if they provide the tuner and the tune. In our case as mentioned, based on our mods (removing CAT only) he felt we hadn't changed anything that would affect the warranty.
That would be the dealerships that don't follow the intent of the Magnusen Moss Warranty Act here in the US. Which, in short, says that a modification has to be directly related to the failure in order to void the warranty claim.
The MoCo put a new motor (complete) in my wife's bike at 30k miles and a complete rebuild (flywheels, lifters, heads, etc.) on my bike at 30k miles both under the factory warranty (hers is an 09 and mine is a 10) and we both have cams, tuner, exhaust and she has the high flow A/C. That's the kind of service you get from a good dealership.

Those dealerships that play the warranty game because a bike is tuned correctly, I believe, is the dealerships that will see more and more business decline........and wonder why. They don't realize that us owners are willing to travel a little further to get great customer service.