Hi guys. Have an exhaust leak and am taking off old manifolds. While I have to do it, will be replacing them with Gibson headers. Anyone put these on? Will also be upgrading my exhaust with Flowmaster 17400 American Thunder cat back system. Would like to take my cats off, but don't feel like fooling with getting custom pipe. The headers are the Gibson GP309S. Any thoughts and should my power go up a bit? Thanks for the info

 

Headers on the 4.7 are a waste actually. Just fix what you have, get the nice new exhaust and call it a day with the trouble and saving kept in your pocket.

 

Removing the cats would make your onboard computers whacky. Best case scenario, you have a constant CEL with the O2 sensor codes, masking/hiding any future codes. You get used to ignoring the CEL, and then one day, a major problem code pops up, but you can't tell until serious damage has occurred because you thought you were just ignoring the O2 sensor codes. Besides, these newer catalytic converters are much better then the older units, they are as good as any high-flow aftermarket units, and the vehicles are designed to run with them anymore. Sometimes removing them makes the vehicle run rough, weird, or with other negative effects. They aren't like my 2001 Ram's unit or before, where they were simple and drastically bad for exhaust flow.

I don't have enough experience with the 4.7 to tell you whether headers are a waste or not, but I can tell you that it is probably better to save the money. Even if they are not a waste, they won't gain much for these big, heavy SUVs, definitely not worth the investment.