If you're planning a fleece 2nd gen swap exhaust brake functionality is probably the biggest question mark on your list. It's one of those things where you really want the reliability and sound of a fixed-geometry turbo, but you don't want to give up the stopping power that makes towing with a Cummins so much easier. When you ditch the factory Variable Geometry Turbo (VGT) for a more robust S300 or S400 setup, you're essentially tossing the mechanism that provides your exhaust braking out the window.
The good news is that you aren't stuck choosing between a cool-sounding truck and a safe-towing truck. You can have both, but you've got to be smart about how you piece the kit together.
Why we do the swap in the first place
Most guys look into a Fleece 2nd gen swap because they're tired of the VGT acting up. Those factory turbos are clever, sure, but they're prone to soot buildup and the actuators fail more often than most of us care to admit. By moving to a 2nd gen style manifold where the turbo sits "center-mounted" and upright, you open up the engine bay and let that 6.7L breathe like it was meant to.
The sound change is the first thing you'll notice. It gets rid of that weird "hairdryer" hiss at idle and replaces it with a deep, throaty growl that reminds you why you bought a diesel in the first place. But once the excitement of the new turbo whistle wears off and you hook up a 15,000-pound trailer, that's when you realize your fleece 2nd gen swap exhaust brake solution needs to be solid.
The loss of the factory VGT brake
On a stock 2007.5 to 2018 Ram, the exhaust brake isn't a separate part; it's just the VGT turbo sliding its internal vanes to create backpressure. When you swap to a fixed-geometry turbo—which is what the Fleece kit is designed for—those vanes are gone. There's nothing there to restrict the airflow and slow the engine down.
If you just do the swap and ignore the brake, you're relying entirely on your service brakes. That might be fine for a street truck that never hauls anything heavier than a dirt bike, but if you're actually using the truck for work, it's a recipe for warped rotors and white-knuckle descents. This is why most people look for an inline exhaust brake to pair with their Fleece kit.
Choosing an inline brake for the Fleece kit
Since the turbo itself isn't going to do the braking anymore, you need a dedicated valve in the exhaust stream. There are a few heavy hitters in this space, like Pacbrake and BD Diesel. These units are usually installed in the downpipe or further back in the exhaust system.
When you're running a fleece 2nd gen swap exhaust brake setup, you want a brake that plays nice with the factory electronics. The goal is to make it so that when you hit that exhaust brake button on your dash, the aftermarket valve closes just like the stock one used to.
Air-actuated vs. Electronic brakes
Most of the high-end inline brakes use compressed air to snap the valve shut. This means you'll need a small air compressor and a tank mounted somewhere on the frame. It sounds like a lot of extra work, but the braking force you get is incredible. It's often much stronger than the factory VGT brake ever was.
There are some electronic versions out there, but in the diesel world, air is generally king for reliability. If you're already running air bags for towing, you might already have half the system installed anyway.
Integration with the Fleece kit components
The Fleece 2nd gen swap kit is known for being extremely clean. They provide the manifold, the oil lines, and all the little bits that make the install look professional. When adding the brake, you have to consider the downpipe.
Most 2nd gen swap downpipes are 4 inches or even 5 inches. You'll need to make sure the inline brake you buy matches that diameter. If you're tight on space—which can happen with the way the 2nd gen manifold positions the turbo—you might have to get creative with where the brake sits. Usually, there's plenty of room right after the downpipe levels out under the truck.
The tuning side of things
You can't just bolt all this on and hope for the best. Since you're removing the VGT, your truck's computer is going to be very confused. It's going to look for an actuator that isn't there and probably throw a handful of codes.
You'll need custom tuning (like EFI Live or EZ LYNK) to tell the ECM that it's now running a fixed turbo. When you get your tunes, you specifically need to tell your tuner that you're adding an aftermarket fleece 2nd gen swap exhaust brake setup. They can map the factory exhaust brake signal to a wire that triggers your new inline brake. It's pretty slick when it's done right—you hit the button, the computer sends the signal, the air solenoid clicks, and the truck slows down.
Performance benefits of the swap
Once you've got the exhaust brake situation figured out, the benefits of the Fleece swap really start to shine. Because the 2nd gen manifold is shaped more efficiently than the 3rd or 4th gen "log" style manifolds, your EGTs (Exhaust Gas Temperatures) will usually drop.
The heat is distributed more evenly across the cylinders, which is huge for the longevity of the head gasket. Plus, fixed-geometry turbos are generally tougher. They don't have the moving parts inside the exhaust housing that can get stuck or heat-cycle themselves into failure. It's a simpler, more "set it and forget it" type of performance.
Installation hurdles to watch out for
Doing a fleece 2nd gen swap exhaust brake install isn't exactly a thirty-minute job. It's a "clear the weekend and buy a case of beer" kind of project. You'll be pulling the factory manifold, which is notorious for having stubborn bolts.
One thing to keep an eye on is the clearance near the firewall. Fleece does a great job with their manifold design to keep things tucked in, but every truck is a little different. When you add the inline brake, you'll also be doing some wiring and plumbing for the air lines. Take your time with the routing—keep those air lines away from the hot exhaust pipes. There's nothing worse than losing your exhaust brake halfway down a mountain because a plastic air line melted.
Is it worth the investment?
Let's be real: this isn't a cheap upgrade. Between the Fleece kit, the turbo, the inline brake, and the tuning, you're looking at a decent chunk of change. However, if you plan on keeping your Cummins for the long haul, it's one of the best moves you can make.
You're basically taking the best parts of the modern 6.7L engine (the displacement, the block strength, the fueling) and pairing them with the best parts of the older trucks (the turbo simplicity and the manifold flow). Adding the exhaust brake back into the mix just completes the package. It turns the truck into a reliable, predictable towing machine that doesn't feel like it's constantly on the edge of a sensor failure.
Final thoughts on the setup
At the end of the day, a fleece 2nd gen swap exhaust brake configuration is the gold standard for many Cummins owners. It fixes the inherent flaws of the VGT system without sacrificing the utility of the truck.
If you're on the fence, just think about the last time you heard a 2nd gen Cummins screaming down the highway. That sound is iconic for a reason. With the right inline brake and a solid Fleece kit, your 6.7L can have that same soul, along with the peace of mind that comes with knowing you can stop that heavy load whenever you need to. It's the kind of modification that makes you fall in love with your truck all over again.