I can tell you right now your going to get attacked for using v-tec and not VTEC (there's no dash) but regardless, if you have a D15B7, you do not have a VTEC engine. The SOHC VTEC engine in the Del Sol's was the D16Z6, same as a '92-'95 Si hatch or EX coupe/sedan. There was also a DOHC VTEC B16A (same engine as your friends 2000 Si) offered in the Del Sol as well.

VTEC is extremely misunderstood and most people don't really know what it is and what it does. Basically a VTEC engine has 2 sepearte cam lobes for the engine to choose from, one for low rpm operation and one for high rpms. For an engine to operating efficently at high rpms, it needs a lot of lift (open the valve further) and duration (open them longer) but those traits also make for engine that has poor low rpm operation and won't idle (ever seen a old muscle car that is very fast but can barely idle, just burbles and tries to die constantly, he's running a big cam).

What VTEC does is allow the engine to idle and run smooth at low rpms and then swtich to the more aggressive cam when your pushing it to give you the best of both worlds. That said, it's only a better cam, it's not a turbo making boost or a nitrous system engaging, it won't throw you back in your seat. The engine will just contiue to make power where as other engines will start to run out of breath. All engines make more power as the rev's climb, especially Honda's so that's probably what your friend was feeling but it's not actually VTEC.