lol, highest I have gone is 185.
dad works for jaguar test facility here in AZ, basically where they do all their hot weather and multi altitude testing. (ie: drives to death valley and back, flag and back, storm chasing, all kinds of crap) he is one of the head techs their for the jaguar division since they share a base with volvo(******* ford) but they have a nice tri-oval track and a road circuit there, drove both an xjr and xkr which make roughly 400hp each. in the xkr got to 185 at the top wide turn before i had to slow down for turn three onto the straight. scared the s*** out of me honestly, was basically running on pure adrenaline and my shaking legs showed it afterword.
racing go-karts back in the day was nothing like this =)
edit: not to get off topic, sorry, the simplest explanation of vtec I have heard is that the camshaft has 2 sets of lobes instead of one, meaning it can use one set for lower rpm and another set for a higher section of rpm. the ecu basically tells it at what rpm to kick into the other set.
all systems are a little different from company to company.