jhonkies

I have a 92 civic, D16A9 motor, DOHC, i bought an DC sports header, but im thinking of changing the hole exhaust pipe, i think about 2", or 2 1/2", if i do this,, hows gonna be the performance of the car?? is it gonna be better? or worse? and how about the sound? i have a muffler too dough..