I just started on it today after work, got the exhaust off, cut the 4" as close to the y as possible, got a 4" id to 3" od reducer from auto parts store, I may not have this done until thursday or friday since work is nuts right now, but as soon as its done and I take it for a spin I will let you know.

 

Sounds good! Curious to know the outcome......
(Wow, 2 puns in one post..... I've REALLY got to watch it.....)

 

ok, Its all done!!!! I will try to insert a picture of my y pipe mod. I Painted it with a very hi temp header ceramic coating to hopefully preserve it longer. on the can it says it takes 7 days to cure It was dry to the touch and worked well during installation, but i'm affraid to run the truck and get it hot before it cures.....any thoughts on that?


hmm, no idea how to get a picture up......

 

Doesn't the heat of the exhaust cure it? (check the can label)
That's what I always thought, but I've been wrong before...... MAYBE a few times....;-)

 

Looking for other's opinions,

I was at first thinking about installing a cat-back exhaust on my truck, but I'm not sure I really want my truck to be loud all the time. My last 5.4L super duty had a Flowmaster 40 on it, and it was fun up until I was trying to have a conversation.

I've been looking at the QTP exhaust cutouts. This seems like it would be an ideal set up to have a loud "aggressive" sounding truck, but be able to run quiet at the touch of a button. I like my truck's quiet stock exhaust for long trips or late at night in the neighborhood.

I don't want to bother with error codes by trying to bypass the CATs, but I don't see there being any room to place a cutout on each pipe after the CATs either. I was thinking of having a local muffler shop replace the front resonator with a Y-pipe, where an electric cutout could be installed.The following link is a Raptor with a similar setup, so it would probably sound similar.

How much do you guys think removing the front resonator would affect the loudness of my stock exhaust?

Oh, and I'm not looking for performance gains, as I know there are not any real performance gains to be had with a Cat-back system anyways.

2010 Ford F150 Raptor SVT DMH Exhaust Cutout Bypass - YouTube

 

which is why I'm gona hold back on the dynomax cat back.

do it the right way man ,headers, and true dual.

I'm going for as loud and clean as possible too though. looking at kooks headers ,and a true dual setup ,dynomax bullets drilled and tapped for the o2 sensors...dual side exit ,or straight rear.. problem with that is.....$$$$$$$
dynomax catback is 550$ , were looking at 3000$ for the true dual setup

 

You actually get better scavenging and power gains thru a correctly-sized single exhaust setup, because that way, pulses from both sides equalize and everything flows more smoothly, actually creating less backpressure, and making more power.
And by the way, many cat-back systems are good for more than 10HP, but the main thing about a good exhaust system is it allows other mods to do their job more efficiently.

 

Well, from all the crap I've been trying on mine, I'm finding that removing the front resinator is a draw back in fuel mileage for sure!, I have gotten a lot of the power back now that I modified the dynomax y pipe to be 3". My current set up is the factory 2 3/4 pipes down from the cats to the y pipe, then it runs into a 4" pipe for 5" in length, then reduces to 3" all the way thru the flow thru muffler and out the tail pipe. It is actually quieter now since I got rid of that 40 inches of 4" pipe. has a nice rumble when you step on it, but is quiet at idle and cruzing. Initial testing shows I got 1 mpg back of the 2 I lost with the other config....guess i can live with that since I got the power back!!

 

Well, from all the crap I've been trying on mine, I'm finding that removing the front resinator is a draw back in fuel mileage for sure!, I have gotten a lot of the power back now that I modified the dynomax y pipe to be 3". My current set up is the factory 2 3/4 pipes down from the cats to the y pipe, then it runs into a 4" pipe for 5" in length, then reduces to 3" all the way thru the flow thru muffler and out the tail pipe. It is actually quieter now since I got rid of that 40 inches of 4" pipe. has a nice rumble when you step on it, but is quiet at idle and cruzing. Initial testing shows I got 1 mpg back of the 2 I lost with the other config....guess i can live with that since I got the power back!!

 

I can see that messing with pipe size (like Dynomax) can affect the scavenging effect, but I wonder if just replacing the front resonator with a 2-3/4" x 3" Y-pipe would affect the mileage? It seems like the flow characteristics should stay the same. By keeping the same pipe velocities, it shouldn't affect performance negatively...but theoretical and real-life often differ.

Ford has likely designed their exhaust system for optimum fuel mileage. Increasing the exhaust diameter reduces back pressure, usually resulting in higher max HP....This also reduces exhaust velocites, resulting in less effective scavenging, which could reduce engine power in lower rpm range (where most of our driving takes place).

 

Well, from reading what happened in the above example, increasing pipe size does NOT always result in more power! In fact in this case reducing the pipe size gained power, because it all has to do with CORRECT pipe size, as I said earlier. And I have a feeling that once the computer "learns" the new setup, more of the mileage might come back, too. Glad to hear the "trick" worked as I hoped it would. I would be curious to see if that 5" length of 4" is still affecting it, and if that could be shortened into a smooth taper from the "Y" into the 3" pipe, but I'm just speculating out loud, and if you're happy with the present setup, just leave well enough alone.

 

Just to add to this. Regular cabs don't come with a resonator. No room for one. My RC has no resonator and seems to get the same gas mileage as others with SC's and CC's. I do still have the stock exhaust although it is a little louder and throatier. I haven't replaced the stock unit because it sounds so good and i get asked all the time what exhaust i am running. People are surprised its stock.

 

I think a little clarification is in order.
The longer wheelbase trucks(non-regular cab) have TWO resonators: The first one that combines both headpipes into a 3" pipe(and is the subject of the above discussion), PLUS another one just ahead of the "main" muffler, that looks like a round can and is about a foot long.

The regular cab trucks eliminate the one ahead of the muffler, NOT the front one with two inlets from the headpipes.

I've looked at both setups, and know this to be true. The second resonator probably has little to no effect on mileage or performance. The one discussed above is the one that the headpipes enter.

I hope this clarifies things a bit.

 

08streetglide,
I was just wondering if you have anymore updates regarding your exhaust as far as do you like it or not, how's the sound, any drone, performance.

I'm asking because I have a 2012 F-350 SD 6.2 CC SB 4X2 and want a cat back system also. I found a system from Magnaflow part #15108 stainless steel,
si/so, right side exit. Thanks for any info.

 

Well I just pulled the trigger on the Dynomax system. It will be a few weeks before I get it but I will keep you all updated.