Thoughts on cat backs. Sound over function? Any before and after dynos?

[Yason84]

This is a pretty restrained conversation talking sound not power gains. I talked to Hennessy. They told me the stock exhaust was plenty as well.

So the only way to get some real hp and torque is to install a K&N filter box for 50 more hp and 100 lbs of torque. If someone installs a Magnaflow muffler between the K&N and the TB there may be another 25 hp available there.

50 hp and 100 tq from just a filter box? Shouldn’t there be other addons you have to do to achieve that? Otherwise I’m gonna have to call bull.

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[amschind]

Flow is determined by the point of greatest resistance. 1 AWG wire connected to a 1000000000 OHM resistor still has basically infinite resistance. The challenge is that the resistance gets higher the closer you get to the head, i.e. the more challenging and costly replacement is.

1) The Dutch Oven manifold is badly designed. You don't need long tube headers to make power on a turbo engine, but man......it's designed to choke the front cylinders AND there is a giant step right before the turbo inlet. Full Race say they''ll have one for the 21+ in the latter half of this year, and while it's $1000 and at least that much to install it, you won't get any extra performance from any other upgrades if your manifold is choking flow right at the heads.

2) The 492 cats. After the turbo and the unfortunately designed manifold, the cats are the next biggest offender. Two high flow cats can dramatically improve flow without making the O2 sensors angry. The larger gain is that IF you also have Aftermarket skid plates, you have the space to give the transmission a little distance from the cross pipe. With zero data but the thoughts in my head, I continue to believe that wrapping the exhaust pipes near the transmission will dramatically cut down on exhaust heat going into the transmission. In terms of "my truck now does things that it could not do before", I believe that this and a radiator upgrade are the two biggest bang for your buck mods that exist. I.e. it's awesome even if it netted you zero power gains, becase the real bonus is that your truck can pull hard without overheating.

3) Cat back. Once you've done the rest of the stuff, you will probably gain from a straight through muffler. I did a Flowmaster DBX with side exit in front of the rear tire. I did this first because I wanted to experiment with getting rid of the PB heat exchanger and deciding if the sound would infuriate me and making sure a side exit in front of the rear tire wouldn't mess that up. The DBX is insulated and mounted where the resonator normally sits. I can touch the surface of the muffler immediately after I turn the truck off. I have the rest of the pipe wrapped because most of the PB electronics are right around it. Further, I have my spare mounted in my bed for easy access, which will allow me to mount a pair of portable gallon gasoline tanks where the spare used to be (since that area is no longer near a hot exhaust pipe). This turned a $3000 Transferflow replacement tank that they didn't seem to want to build anyway into $300 of parts off of Amazon with the added benefit that I can now more easily share the fuel if needed. Obviously the cat back didn't automatically make all of that happen, but it was a necessary step.

Basically I did the process backwards due to parts availability and for User Experience testing. My biggest goal in this isn't a power boost (heh), but having the chance to wrap the exhaust near the transmission. For me, 700 RWHP that can make 3 glory runs is LESS POWERFULL than 380 HP that can run WAO indefinitely. I know that's not everyone, but being able to sustain boost determines how useful this truck is, and the limiting factor is HEAT.

 

[Rinn69]

50 hp and 100 tq from just a filter box? Shouldn’t there be other addons you have to do to achieve that? Otherwise I’m gonna have to call bull.

Pretty sure he was being sarcastic...

 

[UGADawg96]

I gained 50 hp by just changing the knob from Normal to Sport.

 

[CND Supercrew]

I would be curious to know what the sound would be like locked in at 2500rpm, like pulling a trailer for some distance...

 

[Dakar09]

I would be curious to know what the sound would be like locked in at 2500rpm, like pulling a trailer for some distance...

That all depends on what system or exhaust mod you go with. Some aftermarket are better than others at eliminating drone, but cutting off your resonator and muffler and straight-piping it will make things QUITE noticeable inside the cabin.

 

[Eighthtry]

All joking aside, when your factory exhaust system rusts through, the rest of your truck may be close as well. You may want to get those aftermarket exhaust systems sooner rather than later. I believe that Ford, as well as GM, use SS409 in their exhausts. It may surface rust, but that is it. So as long as they are 409 SS or better, they will probably outlast your truck.

For example, my 409 SS exhausts outlasted my truck. It was totaled with 2.200 miles on it. Damage did not look bad. It did get into the frame. That is not unusual and is easily fixed by chopping and welding on a new front factory frame part.

I had a independent shop scan the frame. It was out of spec on each side by 2MM underneath the rear passenger seat. So obvious solution was to replace the entire frame. Just disassemble by running it backwards through the assembly line process, add the new frame, then reassemble it going back through the assembly line, and presto-chango I have my 2200 mile truck back with a lifetime guarantee on the entire process from Liberty Mutual and Carbine Auto Body both.

Guess who was not too happy? Carbine finally looked at it, came up with a real estimate, Liberty choked, totaled it, and we are now down to deciding what a 2023 2200 mile truck is worth with about $4-5,000 of improvements in it. I should have rented a car, but have a 2011 GMC Yukon Denali and a 2018 Z06 laying around that need to be driven, so......

This happened in early February. It is a soap opera. I could go on.

 

[DSvet]

I ended up going 3.5 in from the y pipe to a flowmaster 40 series then dual 2.5 in out the rear. Tucked up high with just the tips sticking out. Looks pretty good for a 600.00 exhaust. I love me some cold starts!

 

[EL5_Zero]

I ended up going 3.5 in from the y pipe to a flowmaster 40 series then dual 2.5 in out the rear. Tucked up high with just the tips sticking out. Looks pretty good for a 600.00 exhaust. I love me some cold starts!

Pictures or it didn't happen lol. Any drone at cruising speeds?

 

[DSvet]

Pictures or it didn't happen lol. Any drone at cruising speeds?

To be completely honest, I don't know what people mean by drone........ I know it sounds good and deep, but not obnoxiously loud when driving normal. But when you romp on it it wakes up and tells anyone around you to move out the way! lol I really do like the cold starts. There's that little fuel dump the pump does and that creates a nice brap then settles. So it doesn't totally wake everyone in the apartments. That and I have two detached garages next to each other, one for the ford and one for the chevy.

 

[gagliano7]

Average horsepower gains are (Gibson) 10-15 and 15-20lb-ft of increase. There are many dynos done that show gains of power for the 5.0 when a cat back is installed. Mandrel bends are the big thing that a good aftermarket exhaust has that a stock one does not.

All of you that say it's just sound and no power gains are welcome to call Gibson, MBRP, Borla etc. and tell them they are wrong. https://gibsonperformance.com/i-227...-3-5l-5-0l-dual-sport-exhaust-aluminized.html

Here is another +9hp +20TQ
https://www.mbrp.com/collections/s5209al-mbrp-cat-back-exhaust-for-2023-ford-f-150-xlt-5-0l-v8

Factory Exhaust is not mandrill bent. There are gains, they are not big but they are gains.
I'm getting the Borla Touring catback when my factory exhaust starts to rust out.

Do you know if that is the regular stock exhaust they are comparing it with or the BAP stock dual exit?

 

[Mtnman1]

No true data to show. I installed the S&B cold air and the Roush cat back exhaust. I love the sound and could be the placebo affect but just feels more snapper at the lights. Plus love the “fox body” sound. Reminds me of high school in the 80’s.

Placebo. Maybe 5hp if you are lucky. No way you can feel that. But you are letting more dirt into the engine. So there's that.

 

[DSvet]

Placebo. Maybe 5hp if you are lucky. No way you can feel that. But you are letting more dirt into the engine. So there's that.

Saying "you are letting more dirt in" is just incompetent.

Everyone from the car manufacturers to performance shops test and use these SRA/CAI's. The filters used are as good or even better than the factory paper filters.
IF you were remotely close to being correct, the manufacturers would void any warranty claims if you added one. Yet here we are where the dealers and manufactures install them on their performance models AND let you even buy extended warranties.

It's posts like this that help spread false information that confuse people that don't actually know anything about mechanics.

 

[Mtnman1]

Saying "you are letting more dirt in" is just incompetent.

Everyone from the car manufacturers to performance shops test and use these SRA/CAI's. The filters used are as good or even better than the factory paper filters.
IF you were remotely close to being correct, the manufacturers would void any warranty claims if you added one. Yet here we are where the dealers and manufactures install them on their performance models AND let you even buy extended warranties.

It's posts like this that help spread false information that confuse people that don't actually know anything about mechanics.

Lol. How do you think more air gets through the filter? Those stock units do a pretty dang good job. They o ky way to increase flow is to remove eesistance in filter.

How is that accomplished?

Show proof that these after market filters do not allow more particulates. And marketing mumbo jumbo does count.

 

[DSvet]

Lol. How do you think more air gets through the filter? Those stock units do a pretty dang good job. They o ky way to increase flow is to remove eesistance in filter.

How is that accomplished?

Show proof that these after market filters do not allow more particulates. And marketing mumbo jumbo does count.

You're the one giving our the wrong information. You prove it lets more dirt in. Seems you know more than those that make the engines, the vehicles, and the filters.

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