I don't see a Fox .15 on that site. Course for the price they want for one, I can't see buying one. I bet I could take it to a local welding shop and have them make one for about the same price, or less. The Fox muffler is pretty good. Not looking at the muffler but it may have a baffle that you could remove for more power. You might try calling Fox for header, muffler sources, they are pretty helpfull.