I was planning on buying headers for my D16y7 but if I remember correctly, the catalytic converter is mounted on the stock exhaust manifold. And when I searched around, I couldn't find anybody that sells 4-2-1 headers for a y7. My question is, does anyone sell headers for y7 and what will happen (with the cat) if I install a new header (will i be 'cat' less)? Sorry I'm still a newbie.

search dude.

You'll need to get a Y8 header, cat from an EX and any exhaust fabrication that needs to be done to make everything fit.