Yeah, I'm not a big fan of flex headers. Not much else available these days, especially with a 50mm drop for this size motor. That's the main reason I chose this motor. 55-60mm would be even better for this plane.
The exhaust port shape is unique to DA. You can make an adapter from aluminum and use the hatori header. Except get the header from RC Japan. It's about 18$ plus 20$ snh.
Regardless, if it breaks you can fix it