Slightly larger diameter intake tube (without the sound deadening part of the stock tube) connected to stock air intake gives more transmitted engine sound.

 

get a spacer for performance(Motordyne Plenum Spacer), sway bars for handling, intake for sound(Pop Charger W/ztube or Stillen Airbox w/ztube)

 

Honestly i would go with the
Motordyne XYZ pipe , they have dynos on their site that actially show significant gains

http://motordyneengineering.com/G35_exhaust.php

Motordyne 5/16 iso spacer

http://motordyneengineering.com/G35.php

and as for an intake, that is just more for sound than performance. just go with a Z-tube and a better drop in filter.

That should keep you satisfied for a while trust me

 

Will the XYZ pipe be as effective with the stock muffler? Would there be anyone for a cop to know its there without putting the car up on a lift?

 

You need a Stillen Gen2 exhaust. See my signature for a link to one.

 

Yes, from what i know, the dyno on their site is an independent dyno for just the XYZ pipe. Correct me if im wrong anyone.
You will not go wrong with motordyne, ever