i've got a 2002 WRX is this mod worth it or does it not effect performance much?

 

I tried it, the hissing/sucking noise when driving gently in town etc annoyed me more than the slightly better breathing cheered me up, so I've put the resonator back in. I think replacing the resonator with a straight pipe gives most of the gains without so much irritating noise

 

I replace the resonator with a pipe, not noticed any difference to be honest