i wouldnt go from 27mm - 100mm. 50mm -100 would be better but still not perfect. if the out let pipe was 36 i dont think there would be a big problem with the overall size of the cyclone. might make it better.
go to your local plumbing shop and see what you can find. iv used black down pipe fittings for things liks this. the end of the hose cuff fits into a down pipe joiner
welcome to the fog.