I have a 2 into 2 exhaust, they're drag pipes and I just put in some baffles to make them a bit quieter. I noticed that my top pipe is black on the inside, and when I run my finger in it it comes out black. The bottom pipe, however, is completely clean - I run my finger in there and there's nothing on it.
Is this bad? Do both pipes deal with the RPM tuning ranges the same way, or it is like the bottom one deals with low RPMs and the top one does the mid and higher ones? I do have a little bit of backfire.
Just caught me by surprise and am wondering if this is something I need to look into.