My truck is a 1998 Silverado 1500. It has about 260,000 kms on it. I am thinking about cutting out the catalytic converters.

Will this create a noticable difference in power, torque, mileage? I am sure by this point in the trucks life they are pretty clogged up and it would make a difference.

Also, has anyone had success doing this themselves? I got an estimate for it, ~$300 to get rid of them and another ~$150 for the sensors or something to be reprogrammed. Will the truck need a reprogramming after the cats are cut?

 

I believe 98's have a sensor before and after the cat. By cutting out the cat the computer will need help reading the after sensor. There is a way to fool it but I don't know how. I have a 95 and my only has one sensor before the cat. I was thinking the same as you and with over 270K on it I too thought I would get more out of my 5.7 if the cat was out. I was wrong. I took a 3/8 rod and ground a point on it and kept ramming it into the cat then I would run the truck to blow out the crap, then rammed some more. once I got a straight through pipe I thought I would be happy. My performance actually went down I guess from lack of back pressure and my mileage stayed the same. The down sides were, my truck can be seen smoking now where the cat would catch the smoke and burn it off, the truck is now cold natured never was before. My truck came with 3" exhaust through out, so yours may preform different. The way cats are made now days they don't clog like they use to. I believe if you had a clogged cat your engine would run pretty bad.
Thanks

 

Because your truck has o2 sensors before and after the cat if it was bad the check engine light would be on. Also you will not get anything noticeable be removing the cat.