Question for FJ with TRD exhaust

[gj1400]

I installed TRD exhaust by my self about 10 month ago.
Today, one of my friend pointed out that inside of exhaust is so black (carbon ?) and may be timing is not right.

Do I need to change any set up for the engine except for disconnecting battery once ?
I thought timing is controlled by chips ???
I have K & N air filter in stock air intake.
Any suggestions ?

[Bostonian1976]

everyone has this - it's weird, I agree - but normal

seems like an engine that is running rich would do this...