I have an 01 F250 SD with a V10 and 98,000 miles on it. I pulled the factory cat, which by that time weighed about 40# from all the exhaust junk it collected over the years. I then put on a Magnaflow cat. Now instead of sounding like a Jap race bike or a loud V6 (like most V10s), it has more of a V8 rumble. One piece of advice: If your cat has sensors in it, and you replace it with aftermarket, you will probably have to reset your "check engine" codes every 2000 miles or so. My sensors are in the y-pipe so I had no worries. Gas mileage improved about 7%, BTW.
As always, YMMV. | 
