The VTEC kicks in at 4400 rpm. you can't notice a sound difference unless you have a different intake and/or exhaust... but at 5800 rpm is the change between the long-throw and short-throw runners on your intake manifold.
Okay. If you pop your hood and are looking straight at the engine, on the right-side of the intake manifold (opposite where the intake pipe connects), you'll see a flying-saucer looking thing that has a vacuum hose attached to it from the bottom. This is the solenoid that switches which runner is being used. Turn you car on and unhook the vacuum hose (don't worry, it won't hurt anything). You should see the little arm coming out of the solenoid drop about 1cm. At this point, you car is using the short-throw (above 5800rpm) runner only. Now put your finger against the vacuum hose - you should feel the suction. If you don't, there's a problem.
If you have a friend available, keep the hose touching your finger so you can feel the vacuum, and have your friend rev the car past 5800rpm. The vacuum should go away above 5800rpm. If it doesn't, well, you know what's going wrong
It should stop sucking, and it isn't. Off the top of my head, I don't remember what the vacuum hose is connected to on the other side, but you'd probably want to check that out.
Hope this helps!