If you going to fit cams your need to do a few other things; the stock car cant be reved above 7200rpm as the stock valve spring retainers are made of plastic ( only joking) alloy so they seem to pull over the valve collets if you try to rev the motor harder. Also fitting cams lowers the dynamic compression ratio so I feel you need to raise the stock compression to make the cams work properly.
We just finshed a N/A DE build , Cosworth heads/HKS cams , Abbey forged rods and pistons , Rev up oil pump , HKS headers , Berks race cats , Cosworth plenum, a lot of the stuff was already fitted before the car came to us with a Piggy back ecu fitted to tune the car for the Cosworth heads/HKS cams etc etc, we 1st remove the piggy back and tuned the car with the Uprev system , then we rebuilt the motor with the forged rods and pistons oil pump etc.
The car prodiced around 310 bgp at the flywheel with the bottom end and 245lb/ft of torque after rebuilding the motor we managed to get 340bhp flywheel and 265 lb/ft of torque still running race cats , then next step is to remove the cats and see if the car gains any BHP/TORQUE.
The car drives so nice but I am still undecided if N/A or S/C is the way to go on a fast road car.
Thats sweet, personally I think it depends the way you drive. Some people love the kick in the back of the boost and some people love stirring the gears on the twisties. I personnaly love the way an n/a drives. I could have got something alot faster than the z for the price but for I dont want all out power and love the n/a power delivery.
I still think your idea of ITB's in an airbox is an ace idea. If it was do able for a decent amount of money I think it would be worth it.