I think I'm the only one on here that has actually done it. I haven't dynoed since and I badly need a tune since I am running very rich. It is very loud (see my other thread) especially with F.I. LTH's which I paired it with. I did it as an experiment and welded 2.5" dual piping to the stock muffler. I'll probably switch to a manufacturer cbe down the line but for some of us, being the loudest car just does it.
However, you won't lose backpressure unless your tubing diameter is greater than 2.5". That would be the max on N/A applications, if you look at the GTM and AAM catbacks they are both true duals that run individual cans and are 2.5" as is F.I.
If you want to hear how loud it is I posted a vid today.
Btw, the power increases are noticeable but I won't have results until I get a tune, which won't be for awhile. My daily commute has become really long so I take my DD a lot and leave the Z at home.
__________________
2009 Carbon Fiber/Red 370z aka Trish: Sports Package, Meisterschaft full catback, Fast Intentions Longtube Headers, Injen Long Tube Intakes, UpRev Tune: Sold 
2008 Lotus Exige S Club Racer aka Bella, always leaves me smiling
|