Whats this then?

I know it alters the fuel i think across the range but how do i set it up? It was on the car when i bought it

That's the first generations apexi air fuel controller, I'm sure you can download the manual of the net.the new ones are the blue screen ones like the avcr

bin it..
alters fueling per revs iirc, 'fools' the ecu AFR reading (dicks about with the voltage before it gets to ecu).. ie. rich or lean, very basic,.. and i'd get a wideband lamda/gauge before doing anything with it imho.

yep as dan said above

old skool piggyback, ok in its day but people boogering around with these and not knowing what afr's actually were blew up many an engine.
you cant be doing stuff like that without a wideband fitted or some sort of det control or its a surefire way to blow your lump up

If i get a wodeband am i right in assuming ill need another female thread ( nut) welding into my exhaust?