Okay I hope I will get an answer this time. I have a 03 civic dx 1.7l soch I have a set of headers from NOPI to put on I'm thinking cause the header is 2&1/4 that I should run 2&1/4 piping to the muffler. Is this right I plan on using a magnaflow muffler but I just want to be sure before I order it.

Thanks for the help