Probably been covered at some point, search didn't help so here goes:

I'm putting together a plan for an upgraded exhaust. The type one exhaust is what I'm thinking of now. I'm going with the universal muffler with custom piping. I have a few questions.

1) Mandrel-bent piping, right?

2) The inlet to the muffer is 63mm. I'm going to try to be consistent and run the same diameter piping back to the catalytic converter. Will my stock cat be able to be used?

3) Is 63mm too much in diameter for my D16y8? Staying NA all the way.

Already have an intake and 4-2-1 header via aem and dc sports.