Outer Limits 4x4 Board

Just wondering as to what sort of power gain will I get from running extractors on my 1HZ cruiser ute, also what upgrades should I do to the rest of the exhaust system to get a good note out of it and abit more power

Not sure how much gain .. but sure less EGT maybe it allow you to push a little more diesel keeping safe your EGTs ... and a 2.5" exhaust sure can help ( again have no numbers how much you will get )