posting this on here for a friends dad.he has a 2000 5.4,off road and is looking at opening up the exhaust a little bit.has anyone noticed a loss in power or increase with the shorties or is it best to stick with the long tube?ive heard of going with shorties and losing low end supposably.looking to see what other people have put on there 5.4's.probably going to go with headers and no mufflers on this.with the cats has anyone hollowed out these or went with high flow cats.ive heard sometimes there isnt even a noticeable difference with changing out for the high flow cats.we were discussing possibly going with some direct fit headers(weather long tube or short)into the stock cats(or high flow if its a major difference)with some true duals with a x or y pipe into some nice tips.the truck has 74k on it so im sure the stock cats are far from clogging up.any questions,comments,concerns are appreciated.thanks ahead.