Recently fitted a Moss Motors Tourist Trophy Exhaust with header.
Came across what appears to be a common problem, the header flange is thinner than my intake manifold flange. Moss explained that they produce a generic size header and expects the standard 1 1/4" washer to be replaced with a fabricated step washer .
I therefore created the step washer you see in the picture which works perfectly. Only wish Moss could provide some warning that there could be a mismatch in flange thickness and suggest a solution.