Exhaust/tail pipe color

I had a good run with the 456 today, a nice drive with fellow F-chatters across one of the country's nicest natural reservation areas. Was a very nice meet & drive.
On the pictures I noticed that the left exhaust is looking very whitish, while the other is nice chocolate brown. I think this could mean it is running lean on the left bank? What do you think?
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Mark, can you explain how that would cause a whitish exhaust? Ceramic material exiting? There are no rattles or other signs of a cat problem.
I searched a bit and found this thread where there seems to be inconclusion about the cause and it's seriousness - opinions vary between not to worry, cats and lean running: http://www.ferrarichat.com/forum/showthread.php?t=255948

I will check the burn image on the spark plugs later this week to see if I can find anomalies there. If it's lean, what could be the most likely thing to cause it? Not the intake gaskets, those have been replaced recently. It's a 2.7 Motronic and it starts/drives great.

 

I'll check it out, mostly worried about a problem with potential to damage the engine. I've read a few things about that the 2.7 Motronic can run lean sometimes and damage parts if it's pushed in that condition.
I have never had a CEL warning on this car. I'll still check out the spark plugs.

How urgent is this if it is the cat? Can I make it till the end of the season?
It probably could eventually clog the exhaust?
Thankfully they only sniff one exhaust side here at the yearly emissions and safety check funny enough. And usually the right one.

 

Thanks Pap, good story, ok so no guarantees then it'll make it
If it's the cats then can put on original OEM but at least one of the cats was replaced on this car about 30kkm ago (now 59k) so quality isn't great then, lasting 30kkm till failure?
Thinking of going to metallic sportcats if that is the issue here. Anyone know if these are available? Hyperflow seems not to carry them. Or would an exhaust shop be able to put in universal racing cats? Hints, tricks, brands to use?

 

Damn, could it be I caught that broken intake gasket too late? It had failed on that very bank.

That I am pretty sure of. Shouldn't be too difficult for them to do and I can have the center resonator removed in the process .

 

Joakim, with the "rubber dissolve" problem, do you mean the rubbers holding the fuel pumps? That rubber doesn't dissolve, it crumbles into chunks that will never make it to the front so the black mess in the manifold probably had a different origin.

The fuel pressure regulators were both renewed in the last service because one was found to be leaking. Measuring the pressure is on the list now.
It used to rough start a bit when warm but drove it for about 3000km this year and that has completely gone away, it just purrs from the first turn of the key. Using something the way it was designed isn't a bad thing.