get good welds and reinforce that rear section at the rear mount, i have cracked mine through there every second race, these AFM one dont have the muffler pick up at the back so the end section swing and vibrate its self to crack.
BRace it, but best is to run a support bar up to the old muffler top mount to the back of the new straight pipe section.
Better to do it now if your MX ing other wise youll be doing at later if you lucky, or picking it up the ground if you let it go for too long