They ok, had one on an old fireblade, sounded nice and deep, not sure how long they would last on a firestorm though, as they do tend to eat cheaper cans. But if you get them cheap enough, I'm sure they would do the job.
I got a used set of alloy ones which I stubbied earlier in the year, pretty well put together and sounded nice before, now sound like the devils farts :-) ill go start it, youll here it wherever you are :-)