1-2 WOT slip after speedo recalibration

So I got some different tires for my wife's 2008 Chevy Impala and I'm having to reduce the speedometer by 10%. Easy enough, I change the tire size by 10% in HPT and have the auto scale transmission tables set to "yes". The speedo is right dead on where I want it BUT under WOT the car slips between 1st and 2nd gear. I put it back to stock for the time being and the slippage stops. No other changes were made. Here's the 2 files for your review. What do you think is causing this? Thanks in advance!

With your speedo scaled have a look at your trans input and trans output reported in third gear. Are you getting a 1:1 ratio?

I didn't change the output ratio so it should still be 1:1. Would that be a problem?