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high flow cats - please advise

7K views 21 replies 15 participants last post by  Challenger370 
#1 ·
I'm seriously considering adding high flow cats to my 2011 RT. Please advise me.

Will they throw codes? Will the car pass inspection? Will they give me low end gains? Better throttle response?

JR
 
#2 ·
I'd just get a set off takeoff exhaust manifolds and cats from an SRT.


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#4 ·
SOLO Mach X
:rocker:
 
#7 ·
Really?
Would it pass a smog inspection that reads from the OBDII cord? or would the HC and Co's be higher making a fail?
 
#9 ·
In Iowa they don't have a emissions test, I think it's still illegal to run without them... Though they would never know.. I've never had one officer look under my car before... Does it ever happen?
How much gains from a cat delete?
 
#10 ·
hey concept.

i have heard 20hp.. now to say that for sure i don't know.. i was looking at solo cats just so i don't have to do to much computer messing with

where you live.. i live in ankeny.

chris
 
#11 · (Edited)
I had Magnaflows previously and Solos currently.
Mags made the exhaust louder but added a bit of drone and caused my check engine light to come on.
Solos didn't change the sound much if at all but did not add any drone and didn't cause any codes.

Neither system increased power enough to be felt by my butt dyno.

Maybe RT's have more restrictive cats and you will feel a benefit, but I personally would have spent the money else where knowing what I know now.

If you don't already have one, a tuner is the best bang for your buck mod you can do IMO.
 
#12 ·
Hey Chris, I live outside Van Meter. You think we'd ever have a problem with cat deletes? I don't want fire coming out my exhaust LOL, but I think it would have a nice tone witout them, not to mention the extra power. I went out for a ride today in the SRT, it was a nice day... tomorrow better. Been a good year for it!
 
#14 ·
Sorry i missed your reply. I dont think we would have a problems with the cats. Alot depends on what brand. Solo claims no codes. Other wise we would have to have a tuner do a tune. And around here there aint nobody that knows sqwat about dodge

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#13 ·
I'm seriously considering adding high flow cats to my 2011 RT. Please advise me.

Will they throw codes? Will the car pass inspection? Will they give me low end gains? Better throttle response?

JR
I have seen about 20 hp from high flows. First they are NOT street legal, and they don't pass emissions.

That said, some companies like soho have figured out how to get around codes, and the states which use the computer to test emissions. Some states don't actually measure the exhaust, they just plug into the computer and ask it, is the cat ok? and if the computer says yes, you pass. The way to get buy with a non street legal car is rear o2 extensions. With the extensions the sensor isn't getting all the data and it "lies" to the computer making it think the stock cats are in place and no codes, and emissions are passed despite the fact the actual gas exiting the tail pipe is exceeding the legal limit.

A car with cat back, or cai is ok with either the stock tune or DiabloSport tunes. If you install headers, high flows, cat delete, camshaft, turbo, supercharger, bore / stroke, any of these or any combination of them require custom dyno tuning.

For example an r/t with shorty headers requires 3-5% fuel. and they produce about 9-10 hp. High flow cats release about double that so, its really going to be lean, and you need a custom tune to be safe, and realize all the hp they offer.
 
#15 ·
I have on my R/T Challenger SRT Stock Shorties, Magnaflow Mids, and Corsa Sport for SRT.

No Check Engine Light - Thanks to Red Barron and B&G Tune
No Drone at any RPM - Thanks to Corsa Sport
0 to 60 went from 5.4 sec to 4.9 sec

I like them, but a set of Factory SRT Mids would be just as good on a R/T IMO.
 
#16 · (Edited)
I have on my R/T Challenger SRT Stock Shorties, Magnaflow Mids, and Corsa Sport for SRT.

No Check Engine Light - Thanks to Red Barron and B&G Tune
No Drone at any RPM - Thanks to Corsa Sport
0 to 60 went from 5.4 sec to 4.9 sec

I like them, but a set of Factory SRT Mids would be just as good on a R/T IMO.
That's good for about +50hp so slightly over 6.1L hp to the rear wheels.

The high flow mids will flow more than stock srt-8, because the stock srt-8 cats are carb certified street legal including California. Other cats are not, because it cost money and because most if not all are high enough flowing they don't meet emissions standards. That's how you get more hp, more flow, more emissions, more hp. When emissions go up, you are quickly over the legal limit, and they know that so they don't even bother testing.

Unless your magnaflow cats are carb certified, then its very likely they have quite a bit more flow than stock srt-8 cats, and give about double the hp gains, around 20 for the cats alone.

The way you don't get check engine light, is they turned off rear 02 sensors with the custom tune.

With that gain in 0-60 your right on 6.1L speeds, so its very likely they are high flows, or in other words much more flow than stock srt-8 and not street legal / more hp than stock srt-8 cats.
 
#17 ·
i'm seriously considering adding high flow cats to my 2011 rt. Please advise me.

Will they throw codes? Will the car pass inspection? Will they give me low end gains? Better throttle response?

Jr
solo mach x
 
#18 ·
By "solo mach x" he means, look at solo, they have figured out how to cheat the system and fake out the rear O2 sensors so you don't get codes. If their inspection is via plugging into the computer, because the computer is being lied to, it will pass that emissions test. If on the other hand they plug a sensor in the tail pipe, they will fail emissions test. They are officially off road only, not street legal. Low end gains, throttle response, about 20 hp, or the equalivant of cat back, cai, and DiabloSport tune combined, or slightly better.

Just remember they will lean the a/f ratio and you need to add fuel. That either requires a wide band O2 welded in, or a custom tune via dyno.

In other words, solo aren't street legal, but they are designed to cheet the system and will pass as long as they don't stick a sensor in the tail pipe. Most emissions testing now doesn't actually measure the exhaust, so for most people it will pass emissions, and not throw codes.
 
#20 ·
The rear o2 sensor is calibrated to the stock cats, high flows don't convert as much of the exhaust to non polluting emissions, therefore they do throw codes. When the a/f ratio is in a safe zone tuning has little to do with the rear o2's throwing codes. Its designed to make sure the cats are reducing emissions, and therefore are restricting flow and reducing hp.
 
#21 ·
I've got the mags and they throw codes. Thinking about using Bigdaddys fix but he wants $80 per side plus shipping up to Canada.

I'd live with the engine light on but if something else ever came up I'd never know.

Maybe I'll get them for my Xmas present. Car is in storage, a good time to do it.
 
#22 ·
Rear O2 extensions are how some venders get around codes. You can get a CMR custom tune and have them turn off the rear O2's as well. High flows REQUIRE a custom tune for a/f ratios to be safe anyway, so you should not only have a custom tune for a/f ratio, but also have the rear o2 turned off.
 
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