Hi Steve,
OK,. had a look on the website and I can see only one size! Had a quick measure and it looks like 25cm long (approx 9.75"). If you are interested, BM me about costs etc.
It is the one I took off my cat this year and is significantly shorter than the one I took off the exhaust!
And it's the alloy one, not the black version.
Thanks!
Darren