I am going to trim my rear fenders so that I can still retain the little flare out on the quarter panel. My question is do I have to do the cut and fold method or can I just sut along that line and be ok? Heres a pic of someone in the process of doing a cut and fold. I want to cut along the line just above where he has cut up too.

 

Also I am planning on putting the black door guard on after I cut them.

 

Cut and fold. There's a bunch of spot welds that hold the outer skin to the wheel well, if you just chop along the line those two pieces of metal can separate and anytime you get in mud or water it'll get thrown into the space between the outer body and interior plastic panels. not good!

Here's some tips for cut and fold: In the corners, make a bunch of cuts close together to help the metal fold prettier. When you make the cut, don't go all the way up to the line, but stop the cut a hair below the line, otherwise it'll look like crap(I've done it, so I know)