well thank you soo much, sta. ill have to do some investigating.

Yes. I'm doing it on a 90 LN3

As to Ryan at GM Tuner'*, Great fellow and he can provide a good starting point for a bastardized engine combination.

Still, you need to develope a working knowledge of how the car'* sensors behave, how the programming responds to that. So, you will need a good scan tool of some sort to be able to tell him what is going on after the changes.

For programming on the fly, an Eprom emulator in place of the stock prom is about the only solution. A cheaper method is to get a stack of eproms and keep recycling them as you make changes.

As for software, I am also an advocate of TunerCat. I use it on several vehicles and it does what it is supposed to do (i.e.what you tell it to do! ) By the same token, it requires an understanding of what to change. In other words, there are no "magic bullets" that will cure all the ills of the automotive world. You need to look at what the car is doing, determine if the problem is a mechanical one or a calibration issue, then make the appropriate corrections (fix the parts and/or change the data as needed.)