Just been into the attick, when I bought the bike it had Akro's on and there was a collector box which I presume must be the standard system. I guess the collector box on mine is for the Akro systems collector box!!
No wonder they wouldnt go on so easily.
My Akro cans must be part of a full system then. I suppose I should strip it all down and start again by putting the original collector box on. Mmmmm.