Which pipe are you running with your nova based P5?

I just got my first gallon or so through this engine and i love it - i'm running an Ofna 053 with a Waller adapter and it has good low end but a little weaker on top than my other engine (OS VZ-B).

i'd like to hear how some other pipes perform with this engine.

Also if anybody has run the 421B, how does it compare to the P5.