How to tell if VTEC is engaging on my 1995 Honda Prelude?

Hello, I have a 1995 VTEC Prelude with an H22. The car has no check engine lights, I have reset the ECU, checked and cleaned the VTEC solenoid screen (which wasn't necessary), full tune-up and engine flush (before screen cleaning). Anyways, in my previous H22 1993 prelude it was very obvious that the VTEC was kicking in, in this car it drives very nice and accelerates good past VTEC crossover rpm limit, but is hard to tell if it's really engaging. The other lude did have a 3" exhaust and this is stock. How can I be sure???