Rokk Tech Silent Might Installed!

[crobertson1]

I just got my Silent Might and had it installed today. I couldn't be happier with it. It's exactly what I was looking for. It gives a little more sound under load, but is quiet in the cab. I was a little leary about changing the exhaust because I like it quiet. This is perfect for me. You can definitely tell it's not the stock muffler, but it is not obnoxious like my 2nd gen with a 4" system and performance muffler was. I haven't towed anything with it yet, but I'm optimistic that it'll be just as good then.



If you're looking for a better sounding exhaust, but still on the quiet side, give this one a try.

 

[MoparBob]

How has the Silent Might been now that you've had it awhile. I have been trying to find a truly quiet exhaust for awhile now. Did you notice quicker turbo spool up? Any drops in EGT? Any drone while towing? Any observations and experiences are greatly appreciated.

 

[JApol]

Ih ave had one on now for about 9 months. It has tones down quite a bit. I don't hear it near as much as I used to at 70 and below 2000 rpm all I hear is slight engine noise. I think it needs some soot to tame it a little

 

[MChildress]

Did you loose the cat?

 

[crobertson1]

How has the Silent Might been now that you've had it awhile. I have been trying to find a truly quiet exhaust for awhile now. Did you notice quicker turbo spool up? Any drops in EGT? Any drone while towing? Any observations and experiences are greatly appreciated.

I'm still very happy with it. I've only towed our TT once so far with it, so my observations are limited. I do believe the EGT has been reduced by about 100 degrees while towing. Before, I could easily reach 1400 degrees without backing out of the throttle. I was deliberately flooring it to see what would happen, it would get hot, but it took effort. That was my main goal, to reduce EGT. I think it worked.



I noticed no drone either. I still have the cat in place. I think it would be too loud for me without the cat. When I had my '01. 5 with a 4" turbo back system with a "performance" muffler, the drone drove us crazy while towing. We don't have that problem now.



I wouldn't hesitate at all to get this muffler. I'm very happy with it.

 

[JApol]

The manufacturer requests that something be in front of the muffler whether be a cat, race muffler or something similiar. When my cat decides to run away i have a jegs resonator to put in its place.

 

[MoparBob]

Thanks for the quick response fellas. How does the exhaust sound while under normal accelaration, at idle, and under full throttle compared to stock?

Would you say it is barely noticeable or a definite change in db's?

 

[JApol]

at WOT the poor guy with his window down needs some some ear plugs. Let off the go pedal and everything quiets down for me. When I first put mine in it did drone at anything over 2000 rpm.

Like i said before it takes some soot to pack in before it quiets down. Moslty I just hear the cummins purr as I head down the road now

 

[crobertson1]

It's definitely louder under load. It to me, sounds like our '93 that's straight piped, but with not as much volume. The same sound, but quieter. I haven't been able to get my wife to drive it so I can hear it from the outside though. Under the bridges and in tunnels, with the windows down, under full throttle, it sounds good. That much I do know.



Did you check out the sound files on the Rokk Tech website?

http://www.rokktech.com/_mgxroot/page_10437.html

 

[betterthanstock]

at WOT the poor guy with his window down needs some some ear plugs. Let off the go pedal and everything quiets down for me. When I first put mine in it did drone at anything over 2000 rpm.

Like i said before it takes some soot to pack in before it quiets down. Moslty I just hear the cummins purr as I head down the road now

If you do a lot of heavy towing, you will get it super quiet around 1800-2500 rpm by reversing the flow direction. SO much quieter, that you don't even need the catalyst, or pre-muffler anymore. Back pressure is still lower than a straight pipe.

 

[Matt400]

If you do a lot of heavy towing, you will get it super quiet around 1800-2500 rpm by reversing the flow direction. SO much quieter, that you don't even need the catalyst, or pre-muffler anymore. Back pressure is still lower than a straight pipe.

Wait a minute. . you mean if I install it backwards I can have quiet and less back pressure than a straight pipe?



How is it less pressure than a straight pipe? With a straight pipe I doubt you could get one pound under WOT. Surely this muffler doesn't suck the exhaust out under vacuum.

 

[betterthanstock]

Wait a minute. . you mean if I install it backwards I can have quiet and less back pressure than a straight pipe?



How is it less pressure than a straight pipe? With a straight pipe I doubt you could get one pound under WOT. Surely this muffler doesn't suck the exhaust out under vacuum.

The exhaust flow is pulsed. The same principle is used by tuned headers and intake manifolds. One pulse helps the next one, within a certain RPM range. It will not develop a vaccuum, but it will lower the peak pulse pressure in the pipe, which allows it to breathe better.

 

[JWilmer]

I'm still very happy with it. I've only towed our TT once so far with it, so my observations are limited. I do believe the EGT has been reduced by about 100 degrees while towing. Before, I could easily reach 1400 degrees without backing out of the throttle. I was deliberately flooring it to see what would happen, it would get hot, but it took effort. That was my main goal, to reduce EGT. I think it worked.



I noticed no drone either. I still have the cat in place. I think it would be too loud for me without the cat. When I had my '01. 5 with a 4" turbo back system with a "performance" muffler, the drone drove us crazy while towing. We don't have that problem now.



I wouldn't hesitate at all to get this muffler. I'm very happy with it.

Thanks guys... . this is JUST what I was looking for... simple, inexpensive, lower EGT's and near stock sound levels..... BJ

 

[crobertson1]

Glad to help! Welcome to the wonderful world of TDR.

 

[Sled Dog]

I just got my Silent Might and had it installed today. I couldn't be happier with it. It's exactly what I was looking for. It gives a little more sound under load, but is quiet in the cab. I was a little leary about changing the exhaust because I like it quiet. This is perfect for me. You can definitely tell it's not the stock muffler, but it is not obnoxious like my 2nd gen with a 4" system and performance muffler was. I haven't towed anything with it yet, but I'm optimistic that it'll be just as good then.



If you're looking for a better sounding exhaust, but still on the quiet side, give this one a try.

Mine arrived today! Oo.

 

[Forrest Nearing]

The exhaust flow is pulsed. The same principle is used by tuned headers and intake manifolds. One pulse helps the next one, within a certain RPM range. It will not develop a vaccuum, but it will lower the peak pulse pressure in the pipe, which allows it to breathe better.

false.



in a turbocharged application, the exhaust coming out of the turbine section is a steady stream flow

 

[betterthanstock]

false.



in a turbocharged application, the exhaust coming out of the turbine section is a steady stream flow

False? Take out your muffler, then tell us what is the "drone" you hear? Is it not pulses at the engine firing frequency? If all you heard thru the tail pipe was turbo whistle, I would agree with you. But the pulses are clearly audible. The turbo does a little bit of smoothing, but obviously not enough.

 

[Forrest Nearing]

those are sound waves, not exhaust pulses... big difference. watch the exhaust out of a gasser on a cold morning... you'll see visible pulses exiting the pipe. watch the exhaust coming out of your truck, steady stream. even moreso when the turbine is spinning at over 100,000rpm



on a 500hp twin turbo small block, going from a chambered (flowmaster style) muffler that is designed to utilize exhaust pulses to a straight through style muffler will pick up about 50hp and the turbos will spool up much quicker.

 

[betterthanstock]

A Flowmaster is designed to break up the sound waves, just like the stock muffler. It will add restriction, not help flow better. It has what are called expansion, and re-entry aerodynamic losses, and many stages that multiply these losses. It's chambers cannot utilize flow pulses at rpm below about 9000-10000 rpm. It's just too tiny for that, and is not tuned to work at diesel rpm. That's why it is good at muffling high pitched sounds, but for deep bass it relies on brute restriction to do any muffling at all.

This is a straight thru, resonated muffler, that you can drop a 4 inch ball thru, something you cannot do with other quasi-straight-thru, like a Banks, Nelson, or Donaldson. There are 5-inch straight-thru Donaldson mufflers out there that have an internal passage of only 3. 5 inches. The aeroturbine is 3" internally. This is 4" all the way. The most free flowing, and the quietest too. It cuts down the bass (the drone) and lets out plenty of whistle.

By the way, all sound waves are pressure pulses.

 

[Matt400]

What makes it more quiet installing it backwards and does that decrease flow from the forward mounting?