I 've dynoed a few Improvers most where in the 215 to 219 range, with one running 224hp.
I didn't get may details from the guy that brought it me,so I can't tell you who built it, he was very hush hush
Cliff yeatman
Advanced dyno
Advanced Dyno,home of the 05 mach-z 1200 triple 4 stroke turbo