Thank you for the insight!
Will do more research and will most likely follow your lead for most of it.
Will do more research and will most likely follow your lead for most of it.
IamFODI wroteNo need for the cooling stuff unless you have evidence that the stock coolers are insufficient.
No need for TAs unless one of yours fails.
Absolutely do not touch the valve covers or the gaskets unless they leak.
I had to replace a valve cover and ponied all the way up for BMW OE, and I'd do it again. I'm sure the NRW ones are fine but I don't like the idea of completely changing the metallurgy of an engine part without a very good reason.
Billet spark plug tubes seem hugely sus to me for similar reasons. If metal ones were better than rubber, it'd be hard to imagine why BMW wouldn't have used them from the factory. I'd be concerned about thermal expansion stressing the valve covers or something. IDK. Seems super unlikely that you could radically change the material used for a part like that on an engine like this and have no downside.
Here's what I recently did before 160k miles. Basically a complete refresh of the rear suspension the whole powertrain downstream of the engine (except the trans itself), and a bunch of other bits and bobs. Super glad I did it. Made a very noticeable difference.

