Honda Car Forum

I drive a 07 Civic Si, and I wanted to see my cars full potential. I don't do this everyday. I also don't like to show off . I am a humble person just trying to make a living. So I went to a straight away road and tested my car. As I was accelerating, at 1st gear. I past 4500 rpm, when all of a sudden, after I hit 6500 rpm my car decelerate back to 4500 rpm at 35 mph and remain constant. Then I shifted up to 2nd gear trying to hit as far as 7000 rpm and same thing happened again. I hit 6500 rpm, then remained at 5000 rpm at 50 mph. After I just stop and drove home.Now I was wondering is that suppose to be normal? I know it's bad to rev up to the red line, but i wasn't trying to. All I wanted is my cars full potential, since this is my everyday use to go from "A" to "B" . I need some explanation to why my civic is like this...