I know some consoles (like snes) had cart's that had special chips. Do you have to destroy a game to get them? Also could I use a bootleg or pirate cart to get the chips? Are there any more methods?
A coprocessor, such as DSP-1, Cx4, Super FX GSU, or SA-1, is far more complex than a mapper. There are two ways to get a coprocessor: cannibalize a donor for its ASIC or recreate it in an FPGA. As far as I can tell, only licensed games have an ASIC. Bootleg or pirate games are instead designed not to need a coprocessor. The only cart I know of that uses an FPGA is sd2snes.