I had 185hp at the wheels with my 2000 1.8Turbo GTI.
And I was on the low side of some of them. 250,300,350 was not uncommon.
I will let you in on a little secret ^_^ They show what is called corrected hp. Basically they add in a huge fudge factor to compensate for the transmission, drive train, alternator, water pump, exhaust, intake, mechanical friction, etc.
When I do dyno runs, I calibrate the machine and compensate for altitude and temperature, period.
Normally aspirated a 1.8 L engine is apx. a 100 hp engine, at a reasonable rpm. If you boost it a lot, 180 to 200 is possible. And yes if you add intercoolers, nitro, tuned exhaust, etc. etc., you can probably even get up to 500 hp and it may last long enough to make it to the end of the quarter mile.
Take hp claims with a grain of salt.