Walms wrote:

This is a bit of a hack but worked great for me, plus you can't see the carnage when assembled...
3/4" copper pipe has the same od as the baffles so I just used a socket to expand the pipe for a slip joint (no welder and no patience...lol). 

On my pipes, the extension goes into a second chamber inside the pipe so you can add or subtract holes to the extension to suit the sound you like.