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Discussion Starter #1
Hi all,

Is it worth it to put high flow cats on my SXT?

If anyone has done this, how did you like it? Did it help the engine breath better? Did it sound any better? Any power gains?

Most importantly, will it void warranty?

Thanks
 

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2016 SXT Plus Blacktop
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Not sure anyone makes any specifically for the Pentastar 3.6. Sure there are generic ones. I think you might pick up a little gain, but suspect it will sound like...

Void emissions warranty, exhaust warranty...quite possibly. Pass smog inspection? Possibly.

I'd think the $ would be better invested in intake/throttle body, cat back exhaust. Tuner. Don't expect a ton of power, 15-20 hp is possible. Hopefully someone has done this and can chime in.

A Guy
 

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I don't know if this is your first mod but if it is its best to start the extreme ends of the induction and exhaust systems. I added a K&N filter, a ported TB and a 93 octane tune but didn't really notice a difference until I installed a resonator delete kit.
 

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Is it worth it? Hard to say. What are your goals for the car?

There are other mods that would be more valuable before you get to replacing your cats. I am with A Guy on this one.
 

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Discussion Starter #5
I have already added a solo performance Cat back exhaust, 80mm TB from Overkill Motorsports, and a Mopar CAI. Im looking into a tune as well.

Honestly I don't really have any goals for the car. I just love working on it and improving it. I know on higher displacement cars, higher flow cats usually means increased power and better sound due to a more free flowing exhaust. I know there is only so much I can do to the 3.6 without adding a supercharger or something but every little bit counts IMO.

But from what it sounds like, my money would be better spent on a tune for the car.
 

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2013 Challenger SXT
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Hi all,

Is it worth it to put high flow cats on my SXT?

If anyone has done this, how did you like it? Did it help the engine breath better? Did it sound any better? Any power gains?

Most importantly, will it void warranty?

Thanks

I did some 1/4 mile testing stock cats vs no cats, without cats the car picked up low end grunt for sure, it was something you can feel and it also reduce 0-60 times. But the car without cats was horrible sounding, it was just terrible, high pitch ricer sound from hell.

Another thing, the stock cats vs no cats in 1/4 mile trap speed- no difference, my e.t.'s came down with out cats, I picked up in 60ft times, which also showed in my over all e.t. was better, if memory serves me right, about .10 quicker over all in the 1/4 mile with out cats, but my mph- trap speed was the same- if anything ever so slightly faster but not enough to warrant the horrible exhaust tone.

I did a write up and can be researched, so my conclusion was the cats mess with gas/exhaust velocity ( hurts low end scavenging) but they are still large enough to handle the volume of gas for upper rpm power and not hold the v6 back.

I did put the cats back on my car and have been running them ever since, I did some testing between a full 2 1/4" exhaust from the cats back to a 2 3/4" exhaust from the same cats back and found ever so slight power increase in the upper end. The larger exhaust did not hurt my 0-60 times in a controlled environment as well. The larger exhaust does make the car feel a little softer down low, but the extra power up top does over come the lost and help improve overall 1/4 mile and 0-60 runs.

To date with other changes as well, I have ran a 14.0 at over 100 mph in the 1/4 and my best 0-60 mph run is a 5.08.

To me the stock cats are just fine. With out them the exhaust tone is so horrible. And even with high flow cats the gains would be next to nothing.

Hope this helps.
 

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The Pork Wagon (‘14 Cop Charger)
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Unless you have a friend with a muffler shop, I'd be surprised if you could actually have someone replace working cats with aftermarket ones. Seems like there's a law or two prohibiting that...at least there used to be, I think?
 

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Discussion Starter #8
Thank you ddeennis, that actually helped a lot. I will not be deleting them or even putting higher flowing ones on. Guess it's time to start looking at a tune haha.
 

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Any benefit to switch from se cats to srt cats?
Considering a total delete of the cats all together was at best .08-.10 improvement in the 1/4 mile with no increase in 1/4 mile mph worth noting, one can assume, I think, that any variation of any cat is going to cost way more than any possible gains, you may pick up some with aftermarket cats and you may pick up some with srt cats- even then I would say no increase in power output based on the test I got no gain in trap speeds (cat vs no cat), you may increase exhaust efficiency down low removing some restriction to improve exhaust scavenging to pick up some low end torque numbers but it would be vary minimal to no gain, considering you would still have a cat to restrict flow/mess with scavenging efficiency.

I played with many exhaust designs, you would be better served having a free flowing exhaust, paying attention to details like, mandrel bent tubing, butt weld everything you can , using high end mufflers that have a true straight thru design with same size piping thru the mufflers as the exhaust pipe.

Many of your cheaper mufflers are necked down in I.D. size than your actual exhaust size, many mufflers are not straight thru design which increase flow restrictions and cost torque and power.

Try to imagine being inside you exhaust pipe at the engine and your on a skate board and heading for the exhaust outlet, you want to roll along as smooth as possible with nothing in your way, any sharp turns or ripples or ledges or walls ( like inside the mufflers) will slow you down, you don't want to duck down either, keep the i.d. the same, make the inside of the pipe as smooth as possible, so those exhaust gases can travel without interruption, those exhaust gases carry a negative pressure wave behind them which help pull spent exhaust gases out of your engine cylinders - which this helps with low speed torque.

Best thing I found for a daily driver, run 2 1/4" pipe right off the cats that is mandrel bent ( factory is 2 1/2"), make a very smooth transition coming off the cats and run a quality 2 1/4" cat back that is mandrel bent with straight thru mufflers with same size I.D. piping as the exhaust, this gives you a nice seat of the pants low end grunt you can feel and does help with 0-60 times.
 

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I think with my mods that low end suffered a bit but bigger gains up top.I have K+N CAI and a Fastman TB.One note is on a highway cruise at 70-80 mph I was showing 30.1 mpg.
 
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