what size exhaust for 2L rs2000

[reddevil6]

Hey im getting a RS2000 mk2 and i want to get a new exhaust for it because atm it had a 3 inch that comes out the side of the car behind passenger door, and not muffled i dont think. now the side exhaust is defectabale right? i was thinking a 2 and a 1/4 inch would be nice, im not sure whats been done to the motor but i know its had head work a new cam and maybe more. and where would a good place to buy from?