Originally posted by Bradness:
"The power loss of the stock Y-pipe is how Ford crushed the pipes together." Correction-the problem with the stock Y pipe is the crappy welding job where the 2 pipes are joined/welded to the flange. Take a close look at it and you'll notice big blobs of weld impeding airflow. The D shaped pipes still have the same cross sectional area, just a different shape. Best bet is to cut the sucker off and weld on a proper collector.
Here is what came off our SE. This is the section where the 2 pipes come together.
