Boosted Chemsit

Ok since i come from the honda world, the big thing is rom editing, opening your ecu and making your own custom chip for around 20 beans in parts,
In the honda world we have uberdata, chrome and turboedit, free rom editors where u can make a stock ecu (throws a code at 3 psi of boost) and turn it into a 3 bar capible ecu running 880cc injectors. Has anyone seen freeware editors for the yotas? specificaly the obd1 truck?

It would be sweet to develop some kinda rom editor if not