Originally Posted by scottmcphee

Don't understand why adjustability is required for anything other than spring fatigue over time.

Don't see the need to overpressure the fuel in the IP, either there is enough pressure to deliver the volume to the delivery valves, or not. So long as there is enough pressure, the valves are full and you get a full charge down the line.

Once the critical pressure is met, what does the extra pressure buy you? Nothing. It can't possibly increase the flow to the injectors. It can't possibly change your MPG or power.

To get the critical pressure, just replace the original spring, or stretch it a bit, as per FSM.

None of the poll options have what I'd vote for, so I didn't vote.