Doesnt really matter what type of brand exhaust. I have only driven a Nur with a HKS Titanium exhaust on thats all + I like HKS, as long as you get atleast 3" if not 3.5" / 4" wont hurt as what R34NRG said.
I just preffer a extra heavy duty single plate, bit more drivable because I had a HKS Twin plate before, it's either IN or OUT. Twin, triple, quad plates just be come a nightmare for every day driving LOL!
But all depends are you using it soley for track purposes or you want it to be driven everyday but have bit of bite, will depend on you clutch set up.
The one I drove was 303kWs at All Wheels. The stock single plate was buring out, not gripping as much so needed up grading but everything else was holding up.
When I drove a Nur, injectors, fuel railing and fuel pump, were fine for the APexi PFC.
Nur's came stock at about 1.1 Bar (15.95 Psi), which is quite abit for stock. Again depends how much boost you wanna run. More Boost = Need More Fuel = Upgrade Fueling System (If stock fuel system cannot cope anymore).
I can't exactly say how much boost unit you need to upgrade the fuel system that why you will probley need to dyno tune it to map out everything and see where needs improvement I guess.
DarkChlid is probley the best to speak to about the Nur as he has got one!
Guess it helps when having the chance just to drive one and which was great experiance.