I have a 1994 civic cx h/b i just purchased with a d16z6 engine. It also has the si/ex instrument gauge cluster and 17" tenzo r rims with lopro yok tires. For some reason once i rev past 6k i lose power and it gets real hard for the engine to rev higher which forces me to shift. I am trying to figure out why this is. My engine supposedly has about 77k miles and i used to have a 93 si and it went happily to 7250. What could be the reason for me not being able to rev as high as this vtec engine should? i have full cat back exhaust with a stock intake but removed air silencer. The engine doesnt knock, burn oil, or give general keys to make me think the engine could be half shot.