Stanadyne believer
Based on my 100k+ miles using Stanadyne, I have found the following:
Mileage increased 823mpg per tank, still increasing
Noise reduced 103dB below and 99. 2dB above truck
Fuel pressure increased 16psi pre-filter, 18psi post-filter
Dyno testing confirmed an additional 721 rear wheel hp/1201lb-ft torque
All kidding aside, my experience with the performance formula has been very good overall. I do notice a noticeable (redundant, I know) decrease in injection noise, slightly smoother running engine and . 5-1. 0 mpg increase in mileage. I continue to use it, and will do so in my 04. 5.
Yep, I really am a Stanadyne believer, to really find out yourself, add half a bottle (pint) to a full tank with the engine running and listen to the difference.