Burger motorsports has what I believe is a spacer for the k5 gt-line. Essentially it just opens the normal ports slightly to give you the good ol whistle. Might have one for the 2.0 stinger. Personally I wouldn't get one. With how it's designed I find it more efficient to keep the piping the same. Only exception was with a JB4 and the rare chance of an overboost, which can be solved with the EWG pig tails.
Burger has a blow off valve setup for the 3.3 that you can put a tial BOV on for about....450 I think.
Correction, K8 stinger store has a HKS setup for the 2.0 for about 350, I'm new so I can't post links. But google stinger 2.0 BOV and go about halfway down the page.