Exhaust Size

[RtN]

Is it the bigger exhaust piping it is the better? Say like 60mm and 70mm etc?

[Feverpitched]

Not necessarily, no. The 'better' diameter pipe will depend on engine size, rpm range and intended use. Having said that, going above 2.75in (70mm) is way overkill on a sub-2L NA engine IMHO

[55EXX]

em1 2.25" would most suitable

[B16bcivic]

on a NA engine you should only be using at least 2.5 Inch exhaust and lower bro. any bigger you will just lose power ( not even a fully worked NA engine will go over 2.5inch. Mines a fully worked b20 and its running on a 2.5in only