Sorry we sometimes call things different things here, my "extractors" have a flat flange bolted to the block then 4x 1 1/4" tubes run from each cylinder which then join into a 2 1/4" at the bottom of the firewall.
here's a pic, hope it helps
Power seems to be up over what was on there before (1" pea shooter) , and since it leans out the motor a bit you usually get a small increase in power, I haven't had it dyno'd though (as them laughing often offends)