what you guys think? should i use the subframes?

i have a pair of subs that came on a mach 1....my friend gave them to me a while back and i didnt really think they were any good....im gonna be getting my stock tq boxes welded on this weekend and i was wondering if these would be any good...they are over 45" long...i think all subframes are pretty much the same right? what do you guys think..ohh yeah their boxed
 
They are very thin, and on the Mach 1 are only held in by some low grade small mm bolts. As stated above, they are better than none. I don't know if they can weld those on or not. I would be against the bolt in method....