just for clarification I have just phoned delkevic uk, they told me that NO gaskets are used on our scoots, metal to metal so to speak, the guy I spoke to confirmed that I had done the right thing too by applying a small amount of sealer to the joints, everything was/ is nice and tight!
mamo, it is possible that in your country the header pipe is a different diameter, but I honestly wouldn't know for sure, I hope this helps!
cheers,
Don.