hay UTE18L
if i were looking for more power outer a N/A fuel injected ca18de motor i would do the folowing on a budget:
1x ga16de cam (more lift) cheaper option proven more power through out rev range.
2x get throttle body machined out slightly bigger.
3x remove the restricting plastic inbetween the pod (filter) to the trottlebody, replace with metal pipe also preferebly cold air inducted..
4x head work, ca18 motor really open up after having head work done.. rev better and much more power. can get anything from port and polish 2 a full 3000$ race head.
5x a good set of tuned length extractors will make a bg difference.
6x ive heard that a set of quad throttle bodys on the non turbo motor really make a difference which u would prolly have 2 run a aftermarket ECU 2 get the the bet outer them.

hope al this info gives u a better idea on what can be done to these motors...