I'm also thinking about a new can and have been doing some research. For totally road-legal cans, the Quill T3
http://www.jbracing.co.uk/quill.cfm and the Carbon Can Company
http://www.carboncan.co.uk seem to be the most popular. No-one seems to have a bad word to say about either.
There are some road legal pipes that have removable baffles for, ahem, race use. The Blue Flame
http://www.blueflameperformance.com/ looks good, and has a choice of four exhaust notes, but customer opinion is very mixed. Some people have had very bad experiences with the company.
There's also a Scorpion
http://www.scorpion-exhausts.com/ road-legal pipe with removable baffle. It doesn't look as nice as the Blue Flame though.
If anyone has any other recommendations I'd be interested in hearing them.