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Old 11-07-2013, 04:30 AM
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Replace main cat?

I have an 03 grand cherokee limited with the quadra drive and 4.7ho. I'm about to replace both my precats with magnaflow high flow universals and am curious about changing the larger third cat to high flow as well. I do alot of towing and do not want to loose any torque and I'm going to be changing as much of my exhuast to 3" as I can. Should I leave the third factory cat stock or swap it to high flow 3". Thanks for any and all help!
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Old 11-07-2013, 06:26 AM
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Re: Replace main cat?

To take advantage of the free flow exhaust I would recommend you get a tuner. I would replace the main cat, but you might lose some low end tq with that setup without a tune. Maybe someone will chime in that did that exhaust without a tuner but on my 99 4.7 I had stock precats, no main cat, with 3" tubing all the way out with a flowmaster super 44 muffler and it was great but I had it tuned.
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Old 11-07-2013, 07:12 AM
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Re: Replace main cat?

Well right now a tune is definitely out of the question financially, just decided to upgrade since the stock precats are done and figured I'd splurge on a nice exhuast to gain a little better mpg As well. Maybe I could keep a little low end torque by swapping the factory main cat for a 2.5" high flow and then open up to 3" after?
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