[Dobs]

Murat, a friend of mine is using Cressi G20 rubbers on a 90cm Comanche gun with 6 mm shaft and he is very happy with the set up. Actually this set up is very popular around here, so I don't think you'll have any problem with the 6.25 shaft. Imersion megaboosters are also very popular here both amber and black.
Thanks for all compliments on my gun!