Ok, my Si is throwing the Catalyst efficiency below threshold CEL P0420 or somthing like that. I can pull the fuse to the ECM and it will go off for about 3 tanks of gas. Previously I posted about bad gas mileage and think the cat may be the cause. I'm in about 25 tanks of gas now and average 25mpg in town and 29-30 HWY with the A/C on hight and running about 75-80 mph. Who makes the least expensive mid-pipe w/o a converter. How do I trun off the CEL light? Saw some spark plug no-foul adapers somewhere, but arent't there some MIL eliminators as well? Where do I get them?