Trinity's exhaust says stage four. what does a stage four exhaust mean... If I have no other mods done to this bike would it still be ok to put it on??

 

think u willl need an efi controller to "re-map" the fuel curves, and i would pull the lid off the air box and get a conversion for a k&n think u might be confused the stages are just packages that are offfered, that stage ur reffering to i think is engine mods like boring etc. personally id stick with the pipe, the efi box and k&n those 3 will do ya faster for sure