I bought a brand new DC5 in August last year. I ran it in gently for the first 1000k's (didn't once redline which was very hard for me) After the first 1000k service I cranked it up to redline and was blown away with the boost the VTEC engine had, it was very noticeable when I hit 6000rpm and really gave me a buzz. After a few weeks that boost seemed to diminish to a point where it wasn't noticable at all. I had a 5000k service a couple of months ago (I mentioned this to the dealership before the service) and it still feels like there is no change in performance when I hit that magic RPM figure. Sometime if I try to rev the car (when it's warm) in neutral (push excelerator flat to the floor) it just coughs and splutters around 5 grand, whats with that!? Bad fuel? Clogged injectors? Have I done something to the engine that I am unaware of by redlining it?

Any advice would be appreciated..