| St4 and ST4S cans have a larger diameter pipe where they join the collector box. There is a very obvious flare of the pipe at the end. These cans appear to be the same diameter all the way to the end. Its difficult to see as its not a fantastic picture on ebay so i might be totally wrong!
You could make up an adapter if they are wrong though.
Here is a pic of my spare ST4 cans for comparison. | 
21-Dec-2005, 10:36 
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