Well, to be honest I forgot about this till just now.

Anyway I pulled the pipe out and its 8" from the baffle to the coupling, and the header is 6 1/2" long and the distance from the header to the glow plug (in plan) is about an inch, so that's around about 15 1/2".

Also it looks about right, and the pipe coupling end is the right diameter. I guess I'll be using this pipe!

Cheers guys!