Wow this was a read lol. Sort of skimmed through it to be honest. And from experience. I own and race a E36 M3 with a Euro S50B32. I used to have a E46 M3 track prep'd car. Now tracking my 335is with small mods. Now I can tell already from driving the e92, the suspension geometry is light years ahead from the E36/E46. BUT.... My E36 M3 was quicker than similar prep'd GT2 cars in the CASC here in ontario. The M3 really started getting heavy E46 on. Now driving the E90 M3. I dont really like it, too heavy the V8 is a amazing motor but way to front end heavy. Im sure if I did the same mods to my 335is im sure it would be significantly quicker than my E36 M3. But what I do like about the E36 or even my E30 M3. Is the feel. The E92 mechanical grip is amazing but still to me lacks the steering feel E30-E36 M.
Now talking oil cooling on the N54. I have never had a oil temp issue on my 335is and that was pushing hard for 30 laps straight in 33C temps.
For BBK... Well Ive honestly never ran BBK. I put a brass pin in the single piston caliper. This doesnt allow the caliper to flex. I run SS Lines, fluid and PFC01 pads. Also lots of cooling.
C5 Z06. Now it a great plantform. Now im not a vette fan to be honest. But I can not take away that its a cheap fast track car. If you use it at a power track like mosport here in ontario. Your gonna pull on any E46 M3. Now I love the E46 M3, but for the $$$ and money to mod it. Put 10k into a C5 Z06 and 10k into a E46 M. The Z06 will walk the E46 M every which way due to the E46 M to be soo expensive to mod. C6 Z06 whole different league lol. just my .02cents