Muffler or NOT

Run the 3" as far as you can. In my testing, switching from a 2.5" downpipe (whole exhaust) and substituting in an 18" length of 3" down pipe and mergingit to 2.5"...that was good for 10RWHP.

No back pressure after the turbo is ideal. It helps spool up (faster). I run 3.5" to the axel and a 3" tail pipe.

Run a straight through muffler. The turbo will also muffle noise as well.

I run this muffler but in a 3.5"...thier site was slow so no link...sorry.
Summit Racing SUM-630805 - Summit Racing® Glasspack Mufflers