I need some help. I have the 5.4L and for my exhaust all I have is a spintech muffler. The sound is ok, but feel could be much louder. A friend of mine was saying to get the resistors cut out and that should open up the sound. I was thinking I need to get rid of the monster cats we have and get the high flow cats. My question is, would removing just the resistors and keeping the factory cats in sound good? Or, if I replace the factory cats with the high flow does that throw off any codes for the O2 sensors? Any help would be appreciated. Thanks.

 

Personally I would go with the high flow cats. Better performance and sound, but you may have to relocate the O2 sensors(not sure cause I have an '03.)If you do it's simply just welding on new bungs for the sensor. Although my truck is throwing codes(I don't have the rear O2's ) the high flows shouldn't throw any codes. Good luck with whatever you choose

 

Magnaflow sells high-flow cats with 02 sensors as an option. look for the specific ones with the sensors. i really want to put them in but i dont think they are legal in California (godamn hippies....)

 

Thanks for the replies guys. I was talking with the local muffler shop and they said the best thing to do would be to get the high flow cats in there. I was qouted $180 to install the high flows and run duals out the back, but I would need to supply the high flows since the one's they carry are not OBDII compliant. I'll let you know how it turns out. Thanks again.

 

Several members have simply removed the resonators and left the front cats,they just install a piece of pipe from the front cat to the pipe where the resonator was removed.i have the high flows on my 2000F-150 w/ the 4.6.I installed them 6 months ago,I left the rear o2 sensors in so I wouldnt trip a cel.the shop did an excelent job on the install,nice deep rumble @ idle,and a very noticeable increase in performance.Now the bad part,I got a cel about a month ago,to make a very long story short,my o2 sensors were not reading the exhaust correctly because of the high flows,causing the cel.I went through new o2 sensors,I tried to turn off the rear o2 sensors w/ my Diablo tuner,I purchased a set of BBK mil eliminators,none of these worked.I was faced w/ either installing a custom tune that would turn the light off,or installing my factory cats to pull everything back to where the light could be reset and go out. after much research and $,I finally fixed my cel by simply installing a set of those spark plug anti-foulers.They removed the o2 sensor out of the direct flow of exhaust,I cleared the code w/ my tuner and the light has stayed out.I wanted to share this w/ you so if you encounter something similar to my problem,you already have a solution.You'll really like the high flows,good luck.

 

Thanks for the heads up. I think I'll just go with the high flow cats. From what I'm hearing it seems to be the best bet. Thanks again guys and I'll let you know how it turns out.