15 should be a good number with what you have.....
Could it be the first versions are that bad? It's something I haven't seen. It has to be the tune that is in it, way out of key.
Something to think about. When chipping cars early on ( late 80s ) we saw 1 maybe 2 hp on the dyno at top engine range ( no rev limit ) say 6500. The big gains were in the mid & low range, flater TQ, better driveability. In your case if nothing changed when you took the unit off........ Got some Jack? Or Jim?

 

I'm now placing the $325 I had reserved for GIAC back in my pocket and backing very carefully, yet quickly toward the door. Don't want to draw attention to myself.