F512M Exhausts

I am interested to know if i change the standard exhaust system on a F512M will i get better performance?, and if so can anybody recommend a system for me.
Furthermore my car runs on unleaded feul, but where i live we dont have all enviromental issues and catalytic converters are not reqiured by law so I was wondering what would happen if i removed them and put straight pipes in their place, will this improve anything in performance.
I am trying to keep the car as original as possible and worry that replacing the exhaust will decrease the value of my car as proper collectors will think its been "Tuned" and this is not good if i ever want to sell the car. Any opinions?
Thanks