After fielding a question or two on this, here is the procedure for the builds.
Simply search BBTCC on the storefront. All 17 tunes are available for free on Turtle's SF. You may try as many as you like. Once you have found one you are interested in, request the tune from Turtle (or through me), and it will be gifted to you. You may request more than one tune, but you are locked into whatever car you start with.
This series is looking like it's going to be a real door rubbing, bumper bumping affair! If your down with some intimately close racing, check it out. The more drivers we have the more entertaining it will be.