MagnaFlow 6 X 18 round muffler

Just installed a 6 X 18 inch round magnaflow muffler with 2 1/2 inch pipes with full tail pipe for now. Brand new but sounds good so far Just loud enough to hear with the radio off at hwy speeds. off throttle very quite. Sounds good revving but not that loud perfect for what I want. No drone. Waiting for the computer to adjust but definitely pulls much harder at 4000 rpm .

https://www.youtube.com/watch?v=4Th1czGxItE

Years of working on race motors for cars and roadracing motorcycles I know that straight through mufflers make the most power but are loud, so I took a chance on running a magnaflow 18" round muffler. After hearing the Off Road Pro-Series (a 14" X 5" round) I really liked it but it seamed too loud, so I decided on the 18" X 6" round. Ovals reduce flow but are good to quiet down big motors. But with 4 cats on a V6 an oval seams over kill and I was right the 18" round keeps it tame while maintaining max flow... I'm also copying Bad Ass Mufflers who uses all round mufflers for his exhaust.

 

Muffler update....
I got to drive the truck all day and I can review my system....

First, just putting the exhaust on was making my computer freak out so I remembered what we used to do was to reset the computer after installing mods to start from scratch....

1. Resetting to computer worked great, now the computer can start fresh from today and drive ability was just like new..
2. Now as the computer was learning my mods it was driving better than the stock exhaust most of the time.
3. Part throttle seams better than with the stock exhaust.
4. Above 3500 it runs much better than stock and revs much faster.
5. My system raises the power curve about 500-800 rpm..
6. I can hear the exhaust up to 60mph, not loud enough for drone but you can hear it in the back ground.
7. above 60, idle or off throttle you don't hear the exhaust or very quite.
8. I would recommend If you want to maintain max torque just replace the muffler and use stock pipe or no larger than 2 1/2"...
9. I would not get 3" exhaust unless you have a SC or turbo...
10. At certain rpms in 3rd gear (2000) when it doesn't down shift it runs worse than stock...
11. It has less snap than stock but pulls better...

So yes, I know a good muffler is a good upgrade for your truck and it will run better but even with a 18" you hear the exhaust most of the time...
Reset you computer after all mods will save you lots of "learning" time and it will run better...

Now I can't wait for the dunes running at 4k rpm it is going to pull hard....

 

Sounds good!

 

So after towing I can say larger exhaust hurts pulling power and reduces torque.
I installed my OEM lift and exhaust and now was time to test them...
So I hooked up my 16' enclosed trailer to see how it goes...
Accelerating is worse with the trailer (about 4000 lbs with gear) with the new exhaust and it is much louder towing. to tow with a smaller muffler would be annoying..
It does seam to hold speed good but accelerating is weaker... I could be running leaner but I think the larger pipe shifted the power curve higher. It still pulls good it just slower than before with the trailer on... It defiantly has less torque/ pulling power below 3000 rpm...

For towing or low end torque stick to the stock pipe diameter....

 

First trip with the new muffler 6 hours up north Wisconsin.
Muffler is getting louder but not bad, growls on take off but quite while cruising.
Just slight back ground noise at Hwy speeds, tires are louder than the exhaust....

Also added the intake spacer ( I'll do a full write up) and the exhaust combined with the spacer are working really good...
Together the part throttle acceleration is great and so far MPG is up but the computer is still adjusting after resetting....
Part throttle acceleration from a dead stop is great and passing is good...
MPG is up so far, but it was running lean but the computer is fixing that...
First fill up 20.1 the best I have ever got and that is with the 32s. Cruising over 75 18.8 mpg normally I get 17 at 75mph...

After my 1000 mile trip up north, adding the spacer is a great mod, passing power with the cat back is great. I was passing cars like crazy even double passing cars, first time truck hit over 90mph in 4 years.

I added the spacer after I added my 2 1/2" cat back exhaust with a 18" round muffler. The exhaust worked good but lost some low end torque but had great top end. I was thinking about getting the spacer, I thought the spacer would work good with the exhaust and I was right.

The combination of my intake mods, cat back and adding the spacer brought everything together and worked great. The truck is just fast and the motor rocks above 3,000 rpm. It feels like a hot rod and I'm finally happy with the motor, it's just fun to drive. I look forward to passing and stop lights.

I also picked up some mileage, I was getting 17 mpg with the 32" coopers at any speed, after the exhaust and spacer I averaged 18.6 with a high of 19.8, my new record high ever. my first fill up was 20.1 but the computer was still running lean.

The spacer in combination with the exhaust and intake work great. If you upgrade the exhaust and/or larger tires get the spacer for the added torque.

 

Yup, opening up the exhaust kills low end torque.

I also discovered exactly the same effect on mine when I removed the stock muffler, and installed a small straight through MagnaFlow muffler with a short tail pipe. Changing to a large 22 inch straight through MagnaFlow muffler and a slightly smaller 2.25" diameter long tailpipe worked great to regain the low end pull. Sounds great... and no cab drone.


Greg

 

Sweet, I like my 18" round, but I'm also thinking about going back to 2 1/4 pipe...
The spacer helped give me a lot of grunt back, I have to test with my trailer...

 

Back from my 2nd 1000 mile trip and the truck is running great... For this trip ran to the Silver Lake Dunes to test the OME suspension and the exhaust.. on the dunes I run 4 low in 3rd gear, with the OME set up I was running 3rd and 4th gear...

This is a short vid of a run around the north side of the dunes. You can see from the vid how responsive the motor is, and the exhaust note (perfect for what I wanted).

https://www.youtube.com/watch?v=11FSnFWcpUs

With the exhaust and spacer the motor is running great. The motor really pulls hard after 3000rpm right where 3 gear puts you. Just hit the gas and you can power slide, drift and fishtail.

The motor is running so good I am staying with the 2 1/2 exhaust, the mid range and top end is too good to mess with...

This is a perfect set up for dunes.
I really want to dyno the truck to see where it is, wish I would have done a base run to compare it to.
Between the suspension upgrade and the motor upgrades I over heated my trans fluid, so now I putting on a trans cooler and going to amsoil fluid...

I still have to pull my trailer with the spacer but I'm sure it will pull better.
Great mod, I'm completely happy...

 

I am new to all this modifications exceptionally exhaust mods. What do you all mean by spacers? what kind of spacer?

 

The 4.0 makes peak torque around 3800-4000 RPM so going bigger on the exhaust can help this but hurt power below 3000 rpm...
The intake spacer goes under the intake making the intake runner longer, increasing torque and low end power...

http://extremetruckperformance.com/?page_id=300

The spacer gives you better low and mid range power and larger exhaust gives you mid to top end power.... The combination works great....

 

Not always true on the straight through part. Tooter did a thread on Magnaflow vs. Flowmaster and there were pretty much the same with Flowmaster actually doing a little better. It was on a 2.7 though.

 

Ya bigger exhaust is bad. You want to keep gas velocity up.

 

He was tuning for low end power and the Flowmaster was a little better and the same on top... He was using a 22" and 2 1/4 pipe...

Ultimately a straight through round will flow more air so I believe it will make the most top end power if matched to the proper exhaust for the engine... I believe tooter could make more torque going to a 2" pipe...

I believe the flowmaster may be the best way to quiet down big HP motors but the 4.0 is not a big HP motor and has 4 cats...

The bigger pipe alone is bad but with the spacer it's great. I need to get to a dyno or the drag strip to see if I will go back to the smaller pipe...

 

Now I added the MAF calibrator and I can say that it helps to fix the Toyota map and increases power and acceleration. Because of the 0-60 thread I ran some 0-60 times. Before the MAF I ran 8.04 and a 8.10 on a cool night, after the MAF and about 15 tweaks I ran a 7.23 after a hour long tuning drive in the hot afternoon...

1. The Toyota computer does not adjust f/a ratio very well for mods.
2. Each mod seamed to make it run leaner and leaner.
3. I had a high rpm lean out.
4. The MAF reduces exhaust drone because you need less throttle to hold speed.
5. Holds speed much better.
6. Towing is much better.
7. The computer shifts to towing mode faster.
8. Still have to ck mpg, but it is adjustable.

So after adding the MAF cal and mapping it I can say it makes the truck run much better. Hold speeds very good and pulls much better.
It is very easy to map with real time data.

Towing is much better, before it was running lean and just would not go with the larger tires and exhaust, now it may be towing almost as good as with the stock tires and may pull better at part throttle. It holds speed and climes hills better than stock and the engine drone is gone with the trailer.

So I have learned that if you are going to add an intake or exhaust you have to remap the computer to maximize the results the stock system is not properly tuned and can't compensate enough for these mods. Just by adding the MAF cal it went from towing bad to good and runs .8 tenths faster 0-60 because it needed more fuel in closed loop and just a little less in open loop and had high rpm lean out.

So after the exhaust, intake spacer and MAF cal it is still weaker at low rpm but makes up for it at high rpm, the power curve is shifted up 500- 1000 rpm.
If I was towing a lot I would go back to smaller exhaust and I still might if I go to larger tires. But for now I think it runs real good I just need to rev it more...

I go back to the dunes next month so I will have another update...