well i talked to the dealership i bought my 08 f-150 from, and they said do not replace the cats! they told me it would void warenty and i will most likly get a CEL because the o2 sensor will pickup that there is too much flow throught the cats. so i anit doin that. but.. anything done to exhaust after cats will be allright as long as the diameter of the pipe isnt to small.
so, i want to get true duals with an x-pipe (no muffler). where do i find an x-pipe at? and is that a good setup?

 

You went to the dealership for this info? That BS they told you about the Hi-flows and O2 sensors is well BS, as long as you get the right parts. You can get a X-pipe off of performancepeddler.com.

 

That is bs. As long as you put the 02 back in it won't get a CEL. That's dumb.

 

Xpipes are cheap on ebay.....

 

It is true that they will void your warranty though. Other than that a set of Magnaflow 94000 series cats in 2.5 with the rear O2 mounted after the cats there wont be a CEL.

 

when i bought my truck i was told anything cut infront of the Ypipe will void the warranty on the Cats. The cats have a federal mandated 8 year, 80,000mile warranty.

Still have yet to test what i was told, or prove it right or wrong with documents, but i guess it doesnt matter since my front cats are hollow

 

I thought it was 7yr 70k, guess I was wrong. I pulled my rears out at 67k so I voided mine long ago

 

ok. that one on performancepeddler.com looks pretty unrestrictive, compared to the ones on ebay.