Whether it be GM synthetic, Redline, or Royal Purple is matter of seemingly personal choice. Either will give you stellar results. The reason why we like the PSC Motorsports reservoir so much is because of the generous capacity and the serviceable built in filter. The filter does a phenomenal job of straining aeration and turbulence out of the PS fluid. The built on plastic / aluminum tank late model PS pumps also do a good job. If you stick with the general guidelines discussed, you will be golden.
Correct me if i'm wrong - isn't this a Mustang application?
If so, TCP actually spec's out a KRC pump package:
http://totalcontrolproducts.com/pump.html
