Help Engine Sensor

[public_enemy]

ok guys an gals

i have a sensor missing off my engine i have no idea what it is or what it does not been there since i got it drives fine with out any help on what it is and does and do i really need it would be greatly appreciated

circled in a pic also this engine pic isnt mine

http://i200.photobucket.com/albums/aa217/public_enemy2007/P1000014.jpg

[medz_vtrturbo]

its not a sensor m8
its the earth for your spark plug feed.
the coil pack kind of thing that plugs into ur spark plugs. wouldnt make any difference to performance not being there. andit also depends which engine u have.

[tif992ss]

Hi its the radio supressor Not the earth for the plugs

[public_enemy]

i have a 99 plate grey rocker vtr

so what does this lil bugger do any1