i own a em1.... i know that vtech hits about 5.6 or 5.7 ish... but since i recently put mah mugen ehause with 2.5 piping and a hi-cat flow... it hit like 6 ish... i also have a j's racing intake.. and mugen headers... can anyone explain why the crossover change?

 

Those things won't change how your ECU engages vtec. Have you changed your tire size or did someone swap out your ECU?