frankmoss wrote:However, I must respectfully disagree
Touche. Yes, good sir, I believe you are correct.
Assuming you don't drop below the threshold where the pumping becomes erratic, (and assuming you allow things to reach a steady state), adding resistance linearly should decrease pressure linearly. I'm not quite sure why I thought this wouldn't be the case. I tested my rheostat with an inexpensive multimeter, and I remember the tolerances being less than 5%. That being the case, specs on the solenoid never appeared after a large amount of research, and I only found one source which gave an inductance value.
These factors combined with the variances in the pumps from the factory mean that a rheostat is still a good idea for finding each machines ideal resistance. Being a perfectionist for accuracy, I will change my initial post to better reflect this reasoning.
If anyone else finds things that I have gotten wrong, please let me know. I want this guide to be the best single-stop how-to possible. Thanks!