I rode with a big gun for a year. I repacked it 3 times and re-riveted it once, then I sold it when it needed rivets and packing again. I think you can modify one to hold together, maybe. It gave good low end power, and ok top end when it was packed. I have had a supertrapp disk type slip on for a couple months. Two bolts rattled out, but I caught it and replaced them. Some packing is coming out in places too. Its better quality than the big gun, but Im still not impressed. The supertrapp with all the disks on it, does have tons and tons more top end than the big gun. My stroker revs quicker with it on for some reason too.
I have a big gun on my yfz right now and it is nice but i have read and heard that nmotion is the way to go, so I would go for the nmotion, looks sickk, and performs awsome.