Exhaust header to mid seal replacement

[smarty156]

I need to replace the 2 seals between the exhaust header and mid section on my 2024 TXT Pro Racing.

Any advice? Remove header or mid box?

I looked at removing the header pipe but can't see how i can get the lower hex bolt out of the barrel as the exhaust is in the way. A normal Allen key will go on but will only turn a few mm before it hits the exhaust or sump guard/frame. 

Any help/tips much appreciated. Thanks.