I was told I could find a powershifting upgrade for the 4L60E that was virtually free. I haven't been able to find it. Any help would be greatly appreciated.

 

I've never heard of a "power shifting" upgrade to the 4l60e. The term Powershifting is generally used in conjunction with manuals....as in matching your rpm to your shift point such that you don't have to push the clutch when shifting.

Can you be more specific? Maybe you're refering to increasing shift firmness....