Prentice...
I have a consignment an I use what they give me on the spark plugs. I do make sure they are gapped to toyota spec..028-.030.

I have a fleet of 7 and I agree that the regulators get tar build up and need to be cleaned. The other thing is the intake manifold gets alot of carbon build up. I end up removing and cleaning as best as I can. The other main trouble I have with them is the wires tend to break from vibration at distributor connection to harness.