My 97' 5.4L scab 4x4 has true duals with no mufflers. Ever since I've put the true duals I feel like I lost mpg. I've been reading forums about high flow cats and they got my interest. Since I'm about to put 305/70/17 tires on it I would like some info about cats or mufflers that would help me out. Would just two high flow cats help or would mufflers help too?

 

Did your driving style change? With true dual straight pipes on my brother '97 4.6 he gained 2mpg on the interstate.

 

I didn't change my driving style. My truck gas 193,000 miles on it and still has original everything except for the starter. It could be that my cats are bad, so thats why I was asking about getting new high flow cats or adding mufflers to help the ol truck out.

 

Have you checked your 02 sensors? If they are original they probably died a long time ago, I think 60k is the recomended replacement. A shop can check them before you buy new ones, they can also test your cat which will probably be cheaper than throwing parts at the truck for the fun of it. If everything is in deed still original a tune up probably wouldn't hurt either (plugs, fuel filter...)

 

I've done a tune up on it. Thanks, I'll get the O2 sensors checked.

 

what size tubing did you use? what motor? did you use an x pipe?-i used 2.25" and x-pipe on my 04 8klb van and i gained alot on the bottom end--i have the 5.4 in it-phil