anyone do this yet??- ive seen where people with 4 cats are doing it but seeing how i've only got 2 from the factory i was just wondering if it would really make that much of a difference sound wise--oh yeah, and my o2 sensors are waaaay before my cats!!

 

Ofcoarse many people have had this done with success. Your truck will realy rumble after hi-flow cats man, really will. I would suggest the part #94306 Magnaflow hi-flow cats. The shop will install them and move the rear sensors to behind the cat and it should work.

You have 4 O2 sensors, first set which are most important, and then the second set should be mounted in the middle of them.

 

06+ Only has 1 pair, not sure if Darren caught that or not. My exhaust guy who installed mine said he installed a set of high flows on an 07 and that it didn't sound much different if it did at all. If you're doing a whole setup wouldn't hurt anything, if you're just swapping the cats out I don't think you'd notice any differences (sound or performance) that would merit the cost.

 

hmm.. I thought all cats had front and rear sensors. Just one set? Anyone have a picture of 2006+ cats?

 

Yeah I was talking about the cats, there's still 2 upstream and 2 downstream O2 sensors. I was just saying that Rumor has it high flows won't be much different than stock, those of us with the 4 cats going to 2 or going to gutted precats will certainly see and hear a difference.

 

first thanks for the replies,but just fyi i only have 2 o2 sensors before the cats and 2 in each cat--just wondering if i move the 2 that are "in" the cats to the down stream side of 2 new high flow cats if it will set off any CEL's seeing how i only have 2 cats from the factory

 

I Guarantee you have 4. Like I said before 2 upstream and 2 downstream. They're probably all before or in the cat.

LOL edited your post.

 

yeah sorry bout that, fingers think faster than brain

 

If you have an aftermarket exhaust it will add loads of sound. The stock muffler is huge. I had my high flows installed with a 40 series flowmaster and the high flows made it roar.

 

yea hi flows set mine off man, runs darn good too!

 

hi-flow cats will make a difference, no matter what anyone days. Removing the factory restrictive & resonating cats for direct flow hi-flows will louden it up for sure. If you dont hear it inside, you definitely will outside.

As for the rear in-cat mounted sensors, I believe the rear sensors get mounted in after the hi-flow cat.

 

thanks for the info--yeah if you've heard my exhaust vid the way it is now i can't wait to see how it'll be with true duals, high flow cats, and 4 inch tips exiting behind rear tires THROUGH box centered between body line and bottom of box!(i had a ZR2 with the exhaust through the bumper and loved it,besides i like to make my exhausts unique)

 

Please post pics of that when you do, i have this crazy idea to do that but before the rear tires.

 

not trying to thread steal but looked like a good place for this question...

I, having an 05 with only 2 cats, cut off the factory muffler and welded on a SI/SO Flowmaster Super 44 and turndown off of factory tubing, before rear axle. It sounds good but i'd like just a little more rumble/volume you know what i mean.

Would instaling hi-flows substantialy give me what im looking for?

Will the hi-flows set off the CEL?

Thanks guys,
SouthernStyle

 

It was my understanding that the 04-05 have pre-cats, it wasn't until 06 that they removed the pre-cats. They're much smaller than the actual cats and harder to see and a PITA to get to/remove. Which is why I just had mine gutted. I added my high flows, gutted the precats and haven't had any CEL, so long as you don't mess with the O2 sensors you should be fine. Darren cut his out all together and I don't think he's gotten a CEL!