Welding exhaust header to mid-pipe ?

[Dean77]

Guys the fit between the exhaust header and mid-pipe (all aftermarket on my 2008 650X-challenge) is very loose (like 1mm play all around). I have tried to find some sort of gasket to fit here , but no luck... PLUS the alignment between the 2 tubes is slightly off ... Any reason why I shouldnt just weld this shut ? there is another join just before the end-can, and I'm sure I would still be able to remove the lengthened header when I need to ?
Any thoughts please ?
Thnanks,
Dean (Benoni)