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cat question/flowmaster ?

storlied

Explorer Addict
Joined
June 20, 2007
Messages
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City, State
Anchorage, Alaska
Year, Model & Trim Level
98 5.0L V8 AWD XLT
On a 5.0:
If I ditch the two rear cats, would I fail IM?

Also, would there be any benefit to getting 3" single out?

This is my plan: Ditch rear cats, Add Flowmaster 50 SUV Series dual in 2.25 (stock size if I'm not mistaken) and have it single 3.00 out.

Would there be any benefit? Would I be better off keeping it dual in 2.25, single out 2.25?

Are there any sensors in the rear cats?
My main concern is emissions. Well.. and performance..
 



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If I ditch the two rear cats, would I fail IM?
...
Ditch rear cats
...
Are there any sensors in the rear cats?
I was not aware the 5.0 had four converters. I thought the two in the 4.0 SOHC was an overkill but I did not know the 5.0 had more.
 






Am I mistaken? Could anyone comment on this?
 






You sure you're not talking about the resonator(s)?

Usually, downstream it goes:
[Exhaust Manifold] ---> [Catalytic Converter] ---> [Muffler] ---> [Resonator] --> [Exhaust Tip]

Resonators are typically cylindrical, just a little larger than the pipe diameter, and closer to the end of the stream:
1367.jpg
 






I'm trying to find some threads that mention it.. I'm not having too much luck. I swear I've read on this forum about it.
 


















So what do you think about the IM testing? Would I have any problems? What about having a single 3.00 out?
 






I have no idea what the performance gain might be but it sounds like a few have discussed it previosly -- its even mentioned a few times in that thread you linked to.

As for the 3.0" out, typically a larger diameter means less "umph" at the low end of the RPMs -- unless there's something to balance it at the intake side (like a supercharger).

But heck, what do I know about engine "performance" ... my Explorer never makes it above 15 mph :)
 






Haha, nice truck btw.. I guess I'm going to keep it 2.25 out. But the cats and IM question still remains.
 






ive got a '98 xlt 5.0 and i put in the flowmaster 50 suv 3 days ago and i left all 4 cats in...left the stock 2.25 duel inlets alone and then went 3" single all the way out and i also pulled the resonator out. no drop in low end torque here and if anything a bit of an increase. also the 3" gave mine a lot deeper tone then my friends setup whos is COMPLETELY identical other than he left the 2.25 single out. its up to you...
 






You have everything else stock right now? Could you post a sound clip? That would be awesome.
 






i wish i could...but i have no way to post any sort of videos or sound clips. HOWEVER, if you go to youtube and check out the user "atfyakuza1976", his videos that are about his exhaust (not mikes) are veeerrrrry similar in sound to mine. i believe he also has the 3" single out.
 






oh yeah...and yes everything else is stock...for now. 3" tip and new fuel filter next thursday, and within the next few months MAC CAI and some osrt of perf. chip.:D
 






So what should I do with this 50 Series SUV Performance Muffler?

Keep all 4 cats?
Ditch the 2 rear cats?
2.25, 2.50, 3.00 out?

Which would make me fail IM?
 






ditch the cats they are lame i hate them haha yes im pretty sure you will fail IM test if you take them off, i did haha. i would go 2 1/2 in and 2 1/2 out thats what i did on my 4.0 ohv. works fine no torque or power loss that i noticed just really loud (=
 






I've got the 5.0 though, a tad different.
 












Alright, so the stock piping is 2.50. Is it the same throughout the whole exhaust line? If so, would I notice any difference at all having the tail pipe being 3.00?
 



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Yes, I have.. awhile back though.

I'm confused.. I keep finding it's either 2.25 or 2.50... this is getting confusing..
 






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