I have had a Flowmaster 40 on my 1998 F-250 5.4 for about two years now and have had on problems! My truck pulls a 33' travle trailer the weight is aprox. 7000 lbs.The heat was so hot that my tip turned gold. I think after that if they were junk that they would have been replaced. I work for a Township and we spread salt all winter. Most of the winter my truck has been exposed to salt and there is no rust! The sound is good and the cab noise is not bad. I have read all about mufflers on this fourm and then I purchased it. I read that you get more HP. After I did there was no change. I read that a K&N air filter will improve your HP. I purchased It and it made no change. But it sounds good! I read all about a chip Yes it was the olny thing that made an improvement. I think if you like it go for it! You only have yourself to blame. Keep it simple and enjoy it.