As with most cars the hood insulation is somewhat unnecessary, further proven by the fact that the factory itself did away with the insulation with the really late models (I guess ’90 or so). As mine was also crumbling I decided to remove it with no noticeable downsides. Stock airbox and filter ...

I have converted my '86 to manual using the original Porsche non-assisted rack from a '82 donor car. Low speeds are a struggle, but in my opinion it's worth it, although I have to admit that the power-assisted 944 rack offers plenty of feel already in it's own right. BTW, I also have a 320mm CS ...

I’m also running my original staggered 15” Fuchs set on my ’86, so I feel your pain. Although it has to be said that here across the pond in Europe we at least have some options also in the factory-correct 215/60/15 size. I have a good previous experience with Continental summer tires, at the moment ...

When I dynoed my NA after converting to Tom's Augtronic (MAP, better injectors, wasted spark) my new hp figure was 167hp, 220nm on E85. Unfortunately I didn't dyno my car before the changes, but it definitely feels peppier than before.

And the 163hp ROW cars typically don't have a catalytic converter, as is the case with my '86..

Even with less doors the Panamera could never match the stunning looks of the GTS.

YMMV, but I'd say 5w40 is the absolute thinnest oil I'd use for these engines, even in colder climates. And what about the ZDDP amounts of this oil, is there any data available on that?

You can replace the stock bulbs with leds for sure. But you should also refurbish the cluster reflectors while it's out, per these instructions:

Don’t do it. Pillar pod gauges are an eyesore without exception, makes your 944 look like a ricer instantly. Never mind what one all-brand shop tech says, I bet you the problem is fixed in no time with all the resources and knowledge here at Carpokes..

I can confirm that the bolts you circled in the picture work fine as grounding points.