I used header wrap on some harleys in the past. I wouldn't use them on my car- too much of a pain in the butt to change headers whey they rot out from heat fatigue. If you have your heart set on them just soak the wrap in water first then wrap from the back foreword toward the engine- that'll get you a better 'shingled' look with the overlaps and the water will help stretch them on tight.

I just started by wrapping a couple times away from the head flange, then reversed overlapping the first couple wraps. If you keep it real tight (wear gloves to keep away itchies) you shouldn't have a problem with them coming unwrapped.

When you get up to the top of each tube, just cut the wrap so that the end won't be seen on top for neatness, then put the stainless zip tie right on top. It won't stop the ragged edge from sticking out, so just zip it tight and try to get enough wrap under it so it can't come loose.

If you position each tie the same way they make a nice rhythm and don't look raggedy. I actually like the way they look tied down with cheezy hoseclamps.

Don't forget to spray them down with the high heat paint to help insulate and protect them. It will also help to keep them tight and stiff. It's normal to get a smoky smelly first ride or 2.

Good luck