I have a 98 civic with a d16y7. All stock accept for a header back hks exhaust and random tech hi flo cat. Since mines a dx it dont have a tach so i installed an aftermarket one. Just a small 2.5in. oneto see what im running at. Well this morning on my way to work i wanted to hit redline since i never have before. Well my impressions redline on this engine is 6950 rpm. But mine would stop goin up directly on 6000. Anyone know why?

 

Your ECU and new tach possibly disagree on the engine rpm reading.