What kind of effect will an exhaust pipe upgrade have on a 96 DX civic coupe ?

If I install a high-performance full exhaust system 2.25 piping(header,TEST PIPE, (NO CAT. CONVERTER)and full exhaust system)will there be any carbon build-up on the rear bumper or will I loose any back pressure;also is there any changes or adjustment that will need to be made (02 sensors differ,ECU issues,fuel/air mixtures differs etc...)for this upgrade to be successful ? BE SPECIFIC PLEASE !!!!