Sounds like its carbon build up which is normal with water vapour....
And it is regular 'road gunk' that is sucked up, vacumned to the rear end, and it sticks there. All C6's do this
I think your fine
Manny thanks as always for your quick reply
I look forward to meeting you and maybe getting that "tune" even though I"m not all that sure what that really is'
Ah, AGVI, always the pot stirer.
If I remember correctly, a tune up includes new plugs, air filter, etc. Parts are changed.
A tune however, only changes that are made are to the computer and no physical parts are interchanged.
Is that pretty much the difference Manny?
It is my understand that this applies only to the C5 and C6 series. Those of us with the more primitive C4 series only have the ability to change the ECM PROM to change to change the 'tune'