How much to cut out for fenderwell headers?

http://s290.photobucket.com/albums/ll278/moparwedden/?action=view&current=100_2742.jpg http://s290.photobucket.com/albums/ll278/moparwedden/?action=view&current=100_2744.jpg http://s290.photobucket.com/albums/ll278/moparwedden/?action=view&current=100_2743.jpg http://s290.photobucket.com/albums/ll278/moparwedden/?action=view&current=100_2741.jpg This One With The Headers. I Cut 10 Inches Wide Out. Then Replaced With Stainless Steel To Cover Up Hole. My Headers Are Huge. Good Luck With The Build, Just Slapped The Motor in Last Sunday.