I've been around a lot of 7's and have never seen such soot as my car is outputting. Just from starting the car in the garage I have developed a huge black oval under the exhaust and it extends a good 4 feet (fades), I've noticed soot on cars parked behind it after starting. It has only began to build up like this for the past month or so.

Personally, I don't know if its just running rich due to colder weather, possibly exhaustive Pettit Fuel Lubricant, or perhaps the eventual destruction of the main cat (only cat). Any ideas?

Fyi: Air Pump sound has changed recently so it possibly might not be running up to par. Car has 59k on chassis, 20k on engine with good compression; 10-8-10 Boost pattern, and heathly levels with all fluids.
Mods: Cold Air Stock Air Box Mod, Downpipe, RB Cat Back, & Reliability Mods.

Thanks for your help!

 

Since you have a DP, the rich initial start-up mixture could cause what you are seeing. The pre-cat was designed to heat quickly and oxidize the carbon. The main cat does not heat as rapidly. If the symptoms disappear as the car warms up, I would not worry too much that the main cat is bad.

 

Might be a little bit of both... I know my car runs really rich w/ The SR over-the-phone-tuned PFC, AND, Power FCs don't opperate all of the airpump functions the same, and consequently can "eat" cats... plus i run the pettit fuel bube... i'm whiping down the rear bumper with quick detailer after practically every weekend.