Also, what it the valet mean setting on these BD's???
That is usually a turned down/stock setting so the valet does not hot rod it around.
I am not into synthetics, I think you are better off using dino and changing it regularly. Synthetic only pays off if you run a bypass filter and extended intervals and then it is about a break even. I like to drain any junk that might get in there out.
The K&N replacement is probably okay although many claim the K&N material does not filter well and lets dirt through. I have not experienced that in my vehicles. The replacement filter leaks because the stock housing is junk.
Lots of places to get gauges, check some of the sponsers of the site. I have Isspros in an overhead. I like the overhead mount location but the actual mount is a piece of junk that gets soft in the sun and deforms.