I use the inner piece of Quadra or US Engines muffler and make a 3/32 aluminum plate to go over the back of it. Cut the pipe or pipes out of the back piece, cut holes and braze or weld pipes to the front piece. No power loss and just as quiet. Now it will fit flush to the firewall which was always a pain in the butt. Will fit other engines as it has a small inlet hole to be cut bigger. Wish I could figure out how to make pictures come on.