So i almost finished the plane. I put the pipe an i didn't need to cut the plane, only the inside parts ..That pipe is lighter that the bifurcated with 50 gr. Inside the plane i put some ceramic paper(2 mm thickness), resist at 1200 gr heat and also aluminum tape. I have to cut the support for the pipe(carbon fiber), to remains fixe and that's all. I also painted in black to see the difference between the two faces and be more visible as a pilot.