I had Helix v2

 

Well, if you find something that works for you, do me a favor and post over here

Turtle and Bestswat know that this question repeatedly comes up when an AWD transfer case ruins someone's MD XYZ plans...

 

i got megan racing V2 resonated test pipes with m2 performance G37 y pipe and megan racing oers system which is middy nd muffler..size of pipes in that order are
stock header 2.25to test pipe 2.25-2.5/y pipe 2.5-3.0/mid 3.0-3.0/muffler 3.0
the smell from the test pipes was bad at first but as the pipes coated with carbon they didnt smell as much anymore..can only smell it if windows r down nd the wind is blowing towards the car..the only thing i had to do after install was have 2 hangers welded to the y pipe because the test pipes didnt have hanger for the stock cat locations..everything fits great but it is loud..