Exhaust Valve Anatomy

[rpr]

I had the MRT Trail Ready Midpipe kit installed a few days ago and the OEM valves were deleted. I’m not sure if pics of the valves have been previously posted but thought I would share if it might help anyone.

All these pics are from the downstream side of the valve:

This is what it looks like in its normally closed position:

This is what it looks like with the valve turned CCW:

And this is what it looks like with the valve turned CW:

In the CCW position the valve splits the exhaust flow and the widest part of the valve is on the upstream side, which will impede flow. In the CW position the valve sits flush with the sidewall so it doesn’t split the flow. I’m pretty confident CW is “fully open” but as you can see it’s far from fully open. These valves look like they still translate to an approx. 30% restriction in the fully open position if you ask me.

 

[John123]

That’s helpful to anyone like me considering baby steps of clamping the valve open.

How do you like the MRT Trail? I’ve been wishing for something that split the difference between the extreme and the trail ie 2x small resonators vs 2x small packed mufflers but I haven’t heard either in person so that idea has little merit.

 

[rpr]

I like the MRT Trail Ready kit so far. It’s the only system I could find that minimizes and almost completely eliminates the BWAAAPS (popping/farting) during gear shifts which I don’t care for at all on a truck.

The best way I can describe the system is to say it moves the needle quite a bit to a more “normal” sounding exhaust. I don’t think I’ll ever love the sound of the exhaust on this truck but I hate it a lot less now.

There are some BMW’s with inline 6 turbo engines that sound awesome so maybe there’s hope, but for now based on all the kits that I’ve listened to this is the best one for me, hands down.

 

[deeve]

What makes the valve open? It does not look servo operated with the spring on there.

 

[rpr]

The pressure from the exhaust flow. In theory it stays closed at idle and opens as flow increases with higher rpm’s.

 

[deeve]

Is it there for back pressure, sound, both or ??

 

[prov431]

I also deleted mine with the MF Xmod exhaust system -- they do provide a valved pipe set up in their kit to replace the OEM valves if you want --- thanks but no thanks Sounds perfect!

 

[rpr]

Is it there for back pressure, sound, both or ??

Couldn’t say for sure, some have speculated it’s primarily to reduce drone.

 

[rpr]

I also deleted mine with the MF Xmod exhaust system -- they do provide a valved pipe set up in their kit to replace the OEM valves if you want --- thanks but no thanks Sounds perfect!

Awesome. Glad you like it. Any video or sound clip comparisons?

 

[Mikey Swift]

Is it there for back pressure, sound, both or ??

Strictly for drone at highway speed.

 

[yoda33073]

I had the MRT Trail Ready Midpipe kit installed a few days ago and the OEM valves were deleted. I’m not sure if pics of the valves have been previously posted but thought I would share if it might help anyone.

All these pics are from the downstream side of the valve:

This is what it looks like in its normally closed position:
View attachment 24353

This is what it looks like with the valve turned CCW:
View attachment 24354

And this is what it looks like with the valve turned CW:
View attachment 24356

In the CCW position the valve splits the exhaust flow and the widest part of the valve is on the upstream side, which will impede flow. In the CW position the valve sits flush with the sidewall so it doesn’t split the flow. I’m pretty confident CW is “fully open” but as you can see it’s far from fully open. These valves look like they still translate to an approx. 30% restriction in the fully open position if you ask me.

I have the MRT Trail rated as well. Im not sure if they left the valves or not. Im curious now. I like the way it sounds though for sure. Im good. Cant take all that volume with the others. I had the MRT Extreme on there too. No bueno on the highway.

 

[John123]

I have the MRT Trail rated as well. Im not sure if they left the valves or not. Im curious now. I like the way it sounds though for sure. Im good. Cant take all that volume with the others. I had the MRT Extreme on there too. No bueno on the highway.

Good feedback, I’m teetering on the mrt fence.

 

[Guest1897]

Thank you for sharing. I have never had a vehicle where the exhaust valves were not electronically controlled, this is just sad. I guess an exhaust valve delete will be one of my first mods if my truck ever gets finished.

 

[prov431]

You can see the ones from MagnaFlow in the box (left side) also are spring operated, although I'm not sure if the spring tension is the same as OEM.....I didn't install them though, as noted above.

 

[rpr]

I have the MRT Trail rated as well. Im not sure if they left the valves or not. Im curious now. I like the way it sounds though for sure. Im good. Cant take all that volume with the others. I had the MRT Extreme on there too. No bueno on the highway.

If they made the cuts where MRT recommends the valves were deleted. I talked to MRT about this and they said they designed the Trail Rated kit to have the valves deleted. I have no drone at highway speeds but I do have some drone in the cab during low rpm acceleration (~2,000 - 2,500rpms). Not super annoying, but it’s noticeable. I doubt anything can be done about it but for me it’s a small price to pay for the improvements over the OEM exhaust.

 

[rpr]

I did just get the ANC bypass harness so I’ll report back and let you all know if that makes the acceleration resonance/drone better or worse. Unfortunately, worse is more likely.

Resonators might be in my future…

 

[yoda33073]

If they made the cuts where MRT recommends the valves were deleted. I talked to MRT about this and they said they designed the Trail Rated kit to have the valves deleted. I have no drone at highway speeds but I do have some drone in the cab during low rpm acceleration (~2,000 - 2,500rpms). Not super annoying, but it’s noticeable. I doubt anything can be done about it but for me it’s a small price to pay for the improvements over the OEM exhaust.

Thanks. I love mine too. And I lost the "farting" noise at WO throttle. It sounds better now than it did 4 months ago when I installed it. Dont know why but ill take it.

 

[rpr]

Thanks. I love mine too. And I lost the "farting" noise at WO throttle. It sounds better now than it did 4 months ago when I installed it. Dont know why but ill take it.

Have you noticed any resonance in the cab under mild acceleration in the 2000K - 2800k rpm range?

MRT said the mufflers in the Trail Rated kit are just mufflers, not mufflers/resonators.

I did also notice during the shop install that’s there’s very little room between the mufflers and the driveshaft. I think I’ve seen this in the pics on MRT’s website as well. I doubt that’s an issue though as I see and hear no evidence of interference.

 

[prov431]

These are the SPEQ resonators that I have installed with my MF Xmod -- see images above for the delete and instruction paperwork

 

[rpr]

Very nice system!