Hello everyone new to the forum i have a 5.4 2001 harley truck i have no cel on or lose of power but im getting a knocking sound thats similar to a rod knock but its coming from the driverside top converter coming off the header is this something i can staright pipe since the truck has 2 in the rear .any help would be great.

 

The substrate in the cat is likely broken and moving around with exhaust pulses.
If you have to pass emissions, it needs to be replaced.
Otherwise straight piping may cause a code 430 to be set for bank 2.
Good luck.