Generally you want the bypass pressure higher than 15-20, usually 25-29 seems to be the "sweet" spot. Make sure you use adequately sized bypass hose dont try to make it smaller than they suggest. You can get a USA made bearing if you choose. The seal is almost a universal one for those styles pumps used by many. Also better seals can be found out there at a good bearing supply house. Ive bought a few over the years that were "bad" from folks,