My Etude included a rear mount firewall in the box. I'm sure it would be appropriate for the Himax motor, as I used it to rear mount my Motrolfly 4330 motor. You will likely have to ream out the motor hole in the front of the fuselage to accommodate removal of the motor if that is ever needed. Also, while I was waiting for F3A to get the Etude in stock, Mike sent me a template for the rear firewall so I could cut one out for myself, but didn't need to when one came in the box unexpectedly.