So I got around to getting my test pipes installed today (Thanks TopSpeed & Tony at FI) and figured I'd upload a vid of my setup.
SPOILER: Long story short, I'm thrilled with the result. See vid below. And I do realize that all of that tire squealing at the beginning is probably not the best idea for a "intake exhaust show off thread" but what the hell (and as if the life of NT05's is not already bad enough) 
Video was recorded with a GS4, so by no means the best quality, nor am I the best driver in the world. I hope to record some more videos with a decent cam soon as I don't think these do it much justice compared to in person.
My first mod about 2 years ago was R2C Intakes. Upon installing the intakes I was very surprised with just how aggressive she sounded from under the hood. Slight increase in hp based on butt dyno, but I realize most charts say otherwise.
Roughly a year ago TopSpeed installed the Ark Grip Exhaust. Once again, thrilled with the result in sound and couldn't believe what I was hearing from the R2C/Grip combo. A very deep, aggressive sound under WOT and a beautiful grumble on decel, but I almost think she had too much drone cruising on the highway. My hatch is empty though, so you hear sound and vibration a lot more. With this setup I had zero rasp or high pitched vibrations. Butt dyno once again approved. I got compliments weekly with this combo alone.
So now throw Fast Intentions Non-Res Test Pipes in the middle of it all. I was honestly a little nervous as I've read and heard for myself that the Grip can be a little picky with test pipes, and I definitely did not want to ruin the sound. I searched and couldn't find anyone running this exact setup, so I figured I'd give it a shot. Tony at FI was an extremely helpful/cool dude to deal with, and you can tell he knows his stuff and genuinely loves cars and cares about the customer/quality.
So anyway to the sound...Upon starting her up she sounded slightly louder, more aggressive, even more rumble. Slam the gas and OMG...rasp city...the hiss, that smell. Man there's a lot going on here. I had about a 30 minute drive to work and threw her in about every position I could think of to squeeze every last, different sound out of her. From riding in the car, some sound great, some not so great, some down right annoying. The highway drone is surprisingly less than before, but the hiss on decel is very, very, VERY loud inside the cabin. Butt dyno approved for a third time, but it feels like I need a tune now. Could be in my head. I can say that I ripped it to 80 from a stand still, and then 60-100 like it was nobody's business. This is definitely the most responsive/fastest it's felt.
I was slightly worried about the rasp until I got to work and had a coworker do some drive by's. From the outside of the car is a completely different story. After closing we locked the gates
and recorded a few drive bys in the back parking lot. Hope everyone enjoys!
So future plans... A TopSpeed tune and I'd really like to get a 34 row oil cooler (likely FI). It gets very hot and humid here in GA, and my oil temp year round is a constant 220 upon warming up. Throw in a little spirited driving and she easily climbs to 240+. I like the stock look, so any kind of aero kit or wheels are likely out of the question. I'm running NT05's and have been very happy with their performance. The mound of railroad tracks where I just moved make lowering out the question as well. At some point I'd like to switch to Gen 3's, upgrade the manifold, and possibly swap the headers. I'll likely go with Z1, but there's a small chance I'll go with FI's LTH. I'm waiting on some additional results...
All in all I'm pretty happy with her as is, pending a tune. I just bought a 2000 2.5RS to drive this winter, so I likely won't spend any more money on the Z until Spring 2015. I have some big plans for the RS as well, so I will be torn as to starting a new project or finishing my current. Only time will tell, but there's definitely more to come...
/rant