You wouldn't see much of a difference...because they are the same piece. The difference is in the calibration of the EEC.
The cobra uses a different computer than the GTs do. The reason ur car didn't like the 24 lb/hr injectors is because ur GT computer is set-up to run 19 lb/hr injectors. If you changed over to a cobra EEC then everything would have worked out perfectly.
Now, if you had a mild build-up, a manual tranny, and wanted to go with 24 lb/hr injectors you could then upload a cobra tune if you had a tweecer. That'd make tuning it much easier.
sry...I'm sitting in school right now and just felt like rambling on....