ok im plannin on doin a swap in my civic hatch nd im gonna be doin a gsr swap since everything pretty much drops wrie in from wat i read alot nd it says i need a knock sensor...umm this might sound stupid but wat does a knock sensor do wats it for how much do they cost nd do i realy need it?

 

the motor comes stock with it
all you have to do is wire it up to the ecu

it detects knocks

you may also have to wire up vtec (93-95 civic hatch) and o2 sesnor 4wire if your car didnt come stock with it