Dave
I sat down and worked out the 'sums' involved after Iwas a little disapointed in the amount of extra gas I gained after decanting. I think the difference was 10 bar in the manifold open to closed.
Your mate will struggle though, his twin 7's been 300 bar and the 15 been 232 as it will equalise to the 232. Dependant on how much is in the twins when he decants he might actualy loose gas
