Intake.... either get a decent panel filter or for a bit more noise JTW Pop Charger (or the like)
Exhaust..... Scorpion (nice bark), Milltek (nice sound, bit more money then the scorpion) Nismo (about £1200)
I had a Scorpion and now have a Milltek
As Jay and Martin have said, best way to choose an exhaust is to get to a meet and have a listen