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Two cats are redundant, teh point of the cats is to burn the excess fuel till it is in an emission acceptable state. Once the air passes through the cats its pretty much as burnt as a cat will get it, You can do the spark plug mod if you want to burn anything after that, but I doubt even that would be worth the time youve put into it in the end. Having the resonator on their will help control the sound, but shouldnt do anything to muffle the sounds. Thats what the muffler is for, mine is not loud at all. Not even close. Im considering the new flwomaster VS i guess its called.... Its got the vacuum acuated chambers like the new corvettes. muffled at cruise, but straightflwo at WOT. Im interested to see how the 4.0 sounds with it.
