I have had Schumaker, CPPA, and fenderwell headers on Darts, Barracudas and currently my Duster.
I had some problems with tire clearance like many have pointed out with FWs. And, watch out for those speed bumps. They rattled on the floor board or master cylinder when the car was idling. And, people would eh and awe about those huge headers ramping up and then out the fenderwells. A little awe factor...for some.
Actually, in going with the newer lightweight master cyl I had the adapter slotted a bit so I could move the MC up away from the header. It bought me about 1/3 of an inch. I also moved the motor back about 1 inch to help with tire clearence. It still rubs a little, but I've got tall tires up front.
I didn't like having to remove the drivers side CPPAs to replace the starter.
I also didn't like the fact that the underchassis headers would melt my B&M shifter cable. I finally used a special cover to protect the cable, but what a pain.
The Schumaker Tri Ys were ok for a step between stock exhaust manis and a real header....
So, like many have said before, stock or street use exhaust manis or Schumakers, street strip - it's depends on what you are willing to give up. Strip - fenderwells are the way to go...
My 2 ¢...