with im sure its retard as andy said u can stick it on a RR, floor it and watch the manifold glow red almost instantly........soo much heat cos of lots of boost, but if u advance, turn the boost down (incidentally making more power ) then theirs less heat, and less chance of a fooked farter! bobs yer uncle, now keep to topic lets not do the advance vs retard can of worms (may of got it the wrong way about before anyone points it out)