I use TunerCats not TunerPro for flashing PCM's.

With TunerCats, I start with a 5.7 LS1 Manual Transmission flash and update the engine parameters (fuel tables, spark tables, injector parameters / tables, and MAF tables) to the 5.3 Liter (copy / paste marathon )

Deceleration Fuel Cutoff (DFCO) parameters for a manual transmission are different vs. an automatic transmission, which is the primary reason I start with a manual trans flash.

Perhaps TunerPro has a 5.7 LS1 Manual flash available?

dave w