1). The Boss 302 manifold requires modifications to the stock EVAP purge valve. 5-Star includes instructions for accomplishing this. 2). If you can modify the manifold to avoid beating the firewall, we are not aware of it, though it would not surprise me if someone came up with another method over the years. 3). For a full list of parts and components, please call us directly at 623-434-5277. 4). The BDX tuner does not need to stay plugged into the OBD-II port. The tune is loaded and stored in your truck's PCM, and the device can be unplugged after the tune has been loaded. The BDX comes with SCT "canned" pre-loaded tunes, which won't be compatible with your Boss 302 manifold. This package comes with your choice of 5-Star custom tunes which will be emailed to you after you get us and 5-Star your truck's information via our online tune form. As long as you have 5-Star's tunes in-hand, you can install the manifold and load the tunes the same day.