How important is it to have large diameter exhaust piping for turbo? Will my EGT’s get really high if I’m only using 2.5” versus 3” piping? The last thing I would want is my PSI to spike also because of too small of piping (small piping will cause the turbo to spool quicker).

 

2.5" is fine. Unless your pushing 400whp or so 3" is a waste of money and the time to make it fit.