Dear zthians...need help behalf of my cousin....he had just converted his perdana to a evo3 engine...just seeking some advise on the exaust piping..wats the best size piping can be installed for his car?is it 2.5'' or 3''?currently he is using stock perdana piping with a 2.5'' inlet muffler (tailpipe) connected to his stock piping.his engine mod's are:
