mach1one

here's my problem, i put on an h-pipe and i think the person who put it on took out the catty's and the o2 sensor's my question is this first how do i get the check engine light off? and does this make it have less horsepower? the car seems to bog down when trying a burnout or drag launch.
i have wires to connect the two but some say this just completes the circuit and the car delivers the same amount of fuel because there are no o2's
any help would be great!