sohc vtec

i just hooked my vtec controller up in my single vtec y8 and i rebuilt the motor it works nice and didnt have the vtec hooked up for a while and i hooked the controller up v=afc and was messing with the activation and was letting it kick in at 4500 and then5000 and 5500 the wierd thing is my exhaust is cut so its loud and when the vtec kicks on it gets quiet instead of the opposite of it sapposed to get loud it gets quite the exhaust just shuts up and i dont know the oil pressure is good but it could be the activation i dont know just checking if anyone has this problem?:uhoh:
thanxs