Hi, 3.0/3.2 cams are supposed to be a good (if complex to fit) modification ( I will be trying that on my 2.5 soon so hopefully will be able to report further), while the throttle bodies can prove a bottleneck in the induction system: If you could find someone who can machine the out and smooth the lips, spindles, butterfies ect or find some ready-modified ones that might also liberate extra power. ? :-?
Induction kits...I tried a big sports cone filter on mine earlier and the sound is amazing, lovely throaty roar, and fuel economy was a little better too, but someone said if they are heavily oiled (like some K&N fileters are) that can mess up your MAF sensor. I suppose if you like the noise and can find one that doesnt need to be oiled it could be worth it. Getting cold fresh air into the engine is always important. Superchipping/remapping is another way to go, but if you were going to do any other modifications it would be best to do the remap LAST, so the new settings would work with the increased airflow etc... 8-)