BeardedJag wrote: GM also made a bad choke point in the 3800 series engine on w-bodies(grand-prix, mont carlo etc.) on the downpipe. Whose idea it was to put a dip in the exhaust and put the O2 sensor on top rather than on the side with a straight pipe leading to the cat? Just replacing that alone I think adds 5-10 HP.
O2 sensors last longer when they point straight up and down. That's why.
