getting a standalone to communicate with the rest of vehicle
 

i want to swap a hemi in my grand cherokee, but i dont wanna deal with the bullshit of trying to tune the stock computer. how would i get a f.a.s.t. computer to talk to the rest of the jeep? or is there a certain module that eliminates that all together? i'm not very familiar with chrysler computers.

Just use the stock PCM to control everything except what is controlled by the FAST system.