Cleaning the black pack coated exhausts?

[MiamiBlue]

I want to clean the black exhausts, but I don't want to accidentally damage the black finish and ruin them?

Can anyone recommend a product that will clean them but not damage the coating? (Is it a coating?)

 

[RoryBellows]

Ive just been giving them a scrub with car wash soap. i imagine any will work fine.