The US importer is Hammy the Can Man -
www.hammythecanman.com (I think) - he stocks most of the Blue Flame stuff I think
Before you decide though take a look at
www.trident-exhausts.com - another British company which specialises in Triumph and makes a great product that beat BF in the MCN test a couple of years ago (and everyone else as they won outright as the best can you can buy)