Everyone has a different opinion but here is my take on it

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Mark Perry wrote:
Spark plugs? Stock NGKs should do the job just fine.
Spark Plug leads? i was thinking of using Magnecor KV85's I would get a set of Beru leads (cheap they are not). I have never been that amazed with quality of Magnecor gear often finding genuine gear better in terms of longevity and fit. I know that on my S2 the quality of those leads (stock Beru items) far surpassed anything I have seen from Magnecor
Agreed go with Beru, check cap & arm as they never get changed!
Air Filter? was thinking of keeping the standard setup but using the K+N filter No problems with that. K&Ns however will need cleaning whenever a stock paper element will need changing, not quite the 'fit and forget' filter that they make it out to be.
Stick with standard personally, don't like the cotton type filters. Plenty on the web about issues.
Oil was thinking of Castrol Edge 0W-40 Fully Synthetic I would say that is a little on the thin side for a 944. I would probably go with a good 10W40 or preferably 10W60 (something like Valvoline VR1 or Mobil 1 Motorsport). Some do use a 10W50 with good results. For Mobil 1, if you are ever in the area I am happy to sort you out a good rate on it (I may have a cheap source...)
Go with a good 10w/40 Synth ignore Mobil 1 marketing, plenty about for reasonable money, Halfords is pretty good.
Dizzy cap and Rotor arm? Inspect them and change if there is corrosion/wear present with Bosch/Beru items.
Mark