I have the 1 piece on my gsr because it was cheaper and installing it wasn't as hard as I thought it would be. MY car is pretty low and I couldn't get it jacked up as high as I wanted so I took the driver side wheel off to help me get the header under. And then I had my girl help route it up from the top and it went in smoothly without even scratching it. Just don't forget to put the donut gasket back on the new header before attaching it to the cat or you'll get a bad rattle. learned that the hard way haha