Here are some photo's of my Panacea with an OS160 engine. I used the Hatori wrap around header. I did not need to cut out any holes on the side of the cowling for clearance of the header. You just need to center the header to pipe coupler in the center of the chin cowl and pipe floor area. This can be done using the Hyde type of mount without final drilling the fire wall until everything is fit up. The cowl area is sooooooooooooooo wide on the Panacea, you can hold a dance in the engine compartment.

Good luck - Steve