The only way to get exact numbers, would be to take engine out and run it on
engine dyno, then run out on normal dyno. Also some dynos are not 100% accurate
More often than not, bad tune guys numbers are not right.
One of the reasons on this site, you only ever hear two places,
Desilvas or Petes Performance.
Also weather plays a factor, cooler weather, cars run better,
One of the reasons I likes Petes, Spring New hampshire,
is very close to Nova Scotia weather.
400 HP plus at wheels is more than average drivers can handle, as we see
by endless videoss of guys losing cars when pulling out of places.