Rokktech Muffler

[lawdog]

Has anyone used the Rokktech Silent Might mufler yet. I have read some threads, but looking for "Real World" expieriences, ecspecially while towing heavy. I tow about 10,000 lbs in the winter and can not have loud exhaust in the truck, but would like to lower EGT's a bit.

 

[MikeBeggy]

I installed mine yesterday. I have a Banks 4 inch system with thier monster glass pack and an Aero Turbine all the way forward. The Rokk muffler looks to me to be similar in design to a Flowmaster, only chambers for sound control with no fiberglass packing. The new muffler is 54 inches long overall so it really uses up your space under the truck. You have to fabricate and weld hangers to use the stock rubber system. It seems to flow better and definitely has a different kind of sound. When you get on it, has a very distinctive tuned sound much like flowmasters on a high compression gas big block. It doesn't sound like most other turbo disel loud exhausts I have used or heard. The big surprise to me is at a cruise speed on the interstate,which is near the sweet spot for the Cummins (2000 rpm for me), the exhaust noise is completely gone. I assume that the chamber design is doing it's job at this exhaust pulse. Overall, I'm very pleased with the results. I got tired of the constant noise with the glass pack type of muffler especially when cruising. BTW, I also very satisfied with the Rokk 2 degree advance crank sensor. It's just what my Cummins needed to compliment the other performance enhancements that I have.

 

[67guzzler]

So it's not a Raspy Fart Can (RFC)?

It seems to flow better and definitely has a different kind of sound. When you get on it, has a very distinctive tuned sound much like flowmasters on a high compression gas big block. It doesn't sound like most other turbo disel loud exhausts I have used or heard.

Mike,



I've heard some exhaust systems on the I-6 Cummins and they sound like raspy fart cans. Because of this, I've resisted replacing my exhaust because I wanted to be sure I would get the tone I like.....



Big block gas engines have a unique deep "glup" sound so them & you mention big block gas engines and flowmaster. Knowing what I want to avoid ("raspy fart can") do you think this might be a good choice for someone like me?



Thanks.

 

[JCleary]

I have the Banks system, and after a year and 20k miles it turned into a rasp can, especially with additional fueling/timing. I ended up ordering the MBRP muffler and installing it 10 inches behind the downpipe flange, before the Banks muffler.



Now the tone is very deep, but not any louder than a stock truck... That is, until you hit that "sweet spot. " It's now much more quiet, but I can hear the exhaust at 70mph.



Had I read this post before ordering the MBRP, I probably would have given this a shot.

 

[keimmmo]

If you have a torch and can do some welding, gutting the factory muffler is a good option. You know it will fit! Mine really are not any louder than stock, but do have a slightly different tone under certain conditions. There is NO drone, even while towing in the mountains! It slightly lowered my EGT, improved the fuel ecomony, and REALLY reduced the turbo lag!



If you (or anyone else) are interested, send me a personal message with an e-mail address. I have detailed instructions on how to gut a muffler on my e-mail program, but I have no idea how to get them on here without retyping them.



Steve Keim

 

[MikeBeggy]

JGann, how does one describe a sound? Several trucks ago, I had a mean 502 with flowmasters and it had a very distinct tuned sound. Like a Japanese motorcycle compared to a Harley. Anyway, this system on my Cummins sounds tuned and not that glasspack raspy sound I think you're descibing. I have only run it for a few days but I have already had comments on how different it is.

 

[boonsur]

Does/can anybody provide sound files (digital camera, etc. )?

 

[lawdog]

Mike Beggy, Did you replace the Aeroturbine and the Banks mufflers and just use the Rokktech or all combined ????

 

[mberry]

Does/can anybody provide sound files (digital camera, etc. )?

ROKKTECH has sound files on their website you can listen to. I don't know if that is what you were looking for. I do know that this is the muffler I am going to buy when funds become available. Then when more funds are available I am going to replace the existing exhaust tubing with something else.

 

[boonsur]

The sound files on their website sound really nice (smooth, deep tones) - just like I want.



It sounds like they were done on a 2nd gen truck (non common-rail). Does it sound the same on a HPCR? How about on my '03, without a cat? I think I'm finally ready to spend, but want to be sure.

 

[mberry]

Sounds like a 3rd gen to me. My truck sounds very similar to this when starting and running. It all depends on where they were when they made the recordings.

 

[betterthanstock]

It sounds like they were done on a 2nd gen truck (non common-rail).

The starting clip sounds that way because it was done in a garage, with the mike in the middle, not at the tail pipe. It needs re-doing, eventually...

 

[MikeBeggy]

Lawdog, I have the Aeroturbine as far forward as it could go and about 20 inches of pipe to the front of the Rokktech and then into the tailpipe as it bends up and over the axle. No drone, sounds very tuned. Maybe I just got lucky. The 2 degree timing advance also makes things work and sound better.

 

[lawdog]

Thanks Mike, I just ordered the timing sensor last night... have to save for muffler now. . I will have to try without aero-turbine for now though. . $$$$$ have to hide from wifey... . Im sure she won't notice the growl... . :-laf

 

[Vaughn MacKenzie]

Mike,



I've heard some exhaust systems on the I-6 Cummins and they sound like raspy fart cans. Because of this, I've resisted replacing my exhaust because I wanted to be sure I would get the tone I like.....

JGann the Aeroturbine did wonders for the raspy fartcan sound of my '03. Mike Beggy if you can, get some sound clips of your rig.



Vaughn

 

[p-Bar]

gutting the muff

I am posting this for KEIMMO

Gutting the muffler is a two man job... mainly for getting things apart and back together. You can separate the exhaust

either at the muffler or the extension pipe just ahead of the muffler. Choose the one that the clamp has dented less.

You should be able to get the muffler and tail pipe off the truck together, making less work and not affecting as many

joints.



There should be a guide welded to the pipe that slips into a notch in the pipe/muffler that slips over it. Use a sharp

chisel and remove as much of the guide as possible. It really helps when you take things apart!



To get the exhaust apart, you need someone on the back turning the tail pipe and pulling while someone else heats the

joint... and you usually need LOTS of heat! Avoid wiggling the pipe back and forth as that flairs the end of the joint and

makes it harder to seal later. Twist and pull!



I pulled mine apart just ahead of the resonator. There was enough room after removing the spare tire to slip everything

out the back. My truck is a 2nd Gen... it might be a little different getting things apart on your truck, but the

principal will be the same.



Do not forget to start the truck and see how it sounds without any exhaust!



If you look the muffler over, you can probably see where there is a baffle plate just a little way from both ends if you

have a round muffler. If you have an oval muffler, all the information will be basically the same, but it is harder to

tell where the baffles are and harder to weld back together because it has two layers of metal... an inner and outer layer.

The rear baffle is farther from the back than the front baffle is from the front. Cut the muffler with a hack saw in

the middle of the center chamber or a little toward the back... about the middle of the muffler. It doesn't matter if your

cut is straight or not... just cut it in two. I don't know how many pass tubes there are in your muffler. They are usually

a press fit inside the muffler and will separate if you wiggle the muffler back and forth after you cut the case in two.

If not, you will have to find a way to cut them too without destroying the case.



Leave a little length on the inlet pipe... not over 6 inches behind the front baffle. Angle cut it with a torch with the

long side toward the case and the short side facing the outlet pipe. A pretty angle doesn't matter or if it isn't the

same side to side. Deburr it well on the inside of the pipe. Cut the outlet pipe about an inch from the rear baffle.

This in not rocket science, so cut it with a torch. Use pliers, hammers, or what ever works to flair the end of the

outlet pipe. You will probably have to heat it to bend it into shape. Do not worry about uneven cuts or burrs... just

make a funnel on the end of the pipe. Flairing the pipe is important! A flaired pipe will flow about 25% more that a

pipe that has just a square cut end!!!



If there is another pass tube, remove it completely. Spot weld the pipes to the baffles if there is any question whether

or not they will hold!



I have no doubt that the front baffle will have several holes in it. Leave them. It makes a silencing chamber to reduce

noise. You can as an option weld a patch over a hole or two if there are lots of big holes. If the rear baffle has holes

in it, likewise, leave them. Again, you can weld a patch over a hole or two if there are lots of big holes. Big flat

washers make great patches! Leave the hole/holes open that best align with the inlet and outlet tubes. Again, it will

make a silencing chamber to kill sound waves. If there are no holes in the rear baffle, like my muffler, cut a couple of

1-1 1/2 inch holes in it. Use the torch... neatness doesn't count. Just get a couple of holes for the sound waves to

enter... they can be round, square, or shaped like the State of Texas... it doesn't matter!



Weld the case back together and reassemble the exhaust. Take out for a test drive and come home with a silly grin. If it

helps your truck as much as mine, you will be impressed.



Have fun! Feel free to write if you have questions or comments.



Steve My truck is an '01. 5. The performance difference is amazing... especially the part throttle responce!

Fuel economy improved about 2 mpg. I tow a heavy travel trailer through the mountains. There is NO drone at any speed,

load, or throttle!!! Overall, my exhaust really isn't any louder than stock. It DOES have a slightly different tone under

certain conditions... but NOT louder. If you have any questions about how to gut your particular muffler, feel free to

contact me with questions or comments.