Mentioned several times before but ill mention it again........
Do NOT over tighten the knock sensors.......they are very sensitive
Do NOT drop the sensors......they are very sensitive
Replace BOTH knock sensors AND the harness (I made that mistake once by replacing one knock sensor.....4 months later and I was changing everything out again.)

As far as the RTV or sealent you decide to use on the knock sensor gromets....I RTV'd mine in place and then built a dam around the groments to help gide water around the sensors. You'll notice that your back one will probably be the worst (rusty and probably have some water in it) The foam on the bottom of the intake is up to you. I took mine off because I thought that maybe the foam was holding some water every time I wash my engine (which I do quite often).