Sounds alot like the chip or remap you had done wasnt much cop to me.
As I said, Stealth is known to be optimistic, which makes my 172 optimistic. On a recent Clubgti 16v shootout day at Garage Streamline (using Dyno dynamics - known to be probably the most accurate RR) my car made 162, as did another guys valver, most made mid 150s. There were alot of reference cars there (ie stock/standard cars, that had been well maintained, but were unmodified), which made or nearly made stock VW figures, then the modded cars, such as mine and a few others, showed the gains to be had from various mods. I wont say it is gospel, but I believe it to be as accurate as one can get when quoting car figures.
Check out the results from that day and come to your own conclusions:
http://www.clubgti.com/forum/showthread.php?t=228244&page=14