ROB ROY

I`VE JUST BEEN TOLD I NEED A NEW DOWNPIPE FOR MY94 WRX WAGON (IMPORT.)I`M THINKING ABOUT DOING AWAY WITH THE "CAT", AND WAS WONDERING HOW TO GO ABOUT IT, AND WHAT PROBLEM`S MIGHT ARISE.BEARING IN MIND THE M.O.T.IS DUE IN ABOUT A MONTH.
ALSO WOULD THERE BE ANY DIFFERENCE IN POWER?

I WOULD APPRECIATE ANY ADVICE ON THIS AS I DON`T WANT TO CAUSE ANY DAMAGE TO THE ENGINE.
CHEER`S
ROB ROY.