Tony
Informative & indepth as ever!!
As one or two have commented on here the amount of damage and wear for 50k is shocking. This thread as interesting as it is will now doubt be causing concern / panic for many on here that are running mods on the n54.
Just to try to ease everyones minds a little i think it only fair to push the point that your car whilst regularly serviced has been pushed to the limit & tracked many many times. Whilst the carbon build up is a definate worry (even with a CC) I wouldn't expect anywhere near that kind of wear on engines for the majority of n54 owners out there who are enjoying the performance of thier mods on the road and only exposing the car to medium level temps.
There are probably many on here like myself who drop thier oil every 5k and whilst modded at 370bhp + don't push their car to extreems. Don't get me wrong Ill have times when I drive the car hard but not for extended periods of time and I personally back off everytime my temp gets to 120c.
As you've mentioned alot of the damage is heat related, what sort of temps have you seen on track days?
Best of luck with the rebuild, You really are a pioneer of the n54. Hope you get her back on her feet n fitter than ever ready for some Nurburg action