Looking into getting a muffler but the car is a daily driver so I don't want it to sound like a total race car... thinking along the lines of a B20 or B16A2 in an EK hatch, just wondering if i will loose power on the motor because of the exhaust or if i will end up killing the exhaust ...

the motor will most likely be modded i.e intake,header,exhaust,tb,im

should i go with an ITR muffler or aftermarket? is the flow ALOT beter on an aftermarket or with the itr muffler be good enuff ?