Trans tune is not meant to flush our particular power steering boxes. The seals in the gear box are incredibly prone to leakage and that abrasive of a cleaner is not a wise idea. If you read the owners manual, there is a very specific type of PS fluid recommended for use and it specifically warns against using alternate fluids.

More than likely trans tune is similar to the Lucas product for transmissions that softens seals and causes them to expand and then eventually shred apart.

A simple exchange of ps fluids is all that is needed to flush the system.