I'm using TunerPro DA2. See attached pic.

Perhaps TunerCats has VSS parameters defined, similar to the ones in the pic?

DA2 is not a popular definition, so VSS parameters might or might not be...

Attached is a stock 93 LT1 chip I recently read. Perhaps using the compare feature in TunerPro will help identify the changes to the chip you have?

dave w