The headers have thin metal walls while the factory manifolds are thick cast iron, you'll hear a whole bunch of pings and ticks that will drive you crazy until you get used to it and realize that it's normal. You didn't mess with anything else in the engine correct? And there are no leaks to be found? Not to worry brother, welcome to the wonderful world of long tube headers. Get a louder cat back to drown the header tick and you'll be fine

 

cutout! FTW

 

I love that pinging sound!

 

That's what I did...my favorite "fun" mod so far!