Oil pumps

[flapjack]

what is going on in the world of oil pumps? I see there are several options: Waterman, Titan Speed Engineering, RCD (P&P), and System 1. What is the most popular in TF? I am guessing there is more to pumps than meets the eye, what with tolerances being important when moving such viscous oil.

 

[flapjack]

Ditto for filters. I have never seen them replace a filter between rounds, so I am guessing the nitro soaked oil left in the filter doesn't make much difference, especially since they change the oil after a warm up and that crud will be gflushed out