I know this is mentioned a lot in the I4 etc forum and a lot of officials have been bugged/asked, but please consider tuning for the 2.2 Ecotec in the '03-'07 Ion chassis. I understand there were some PCM issues with the early cars that makes it somewhat difficult to release a single tune, but look at some of the threads and posts and you'll realize that people are looking at $1,900 standalone computer systems in an attempt to tune their cars.
The number of people looking for tuning support is great, especially for the '03-'04 cars as they're either paid off or just about getting there, freeing up considerable cash for modifications. There is one thread that was started 04/02/2004 and has reached 5 pages, 92 replies, and 5,301 views. There is another thread, started 08/17/2006 that has accumulated 45 replies and 661 views. There is staying power in these requests, there are serious customers asking for support.
If you can consider tuning, I would be incredibly grateful and one of your first customers, cash in hand, ready to buy it as soon as it comes out.