The mistake is treating intake flow like CFM is the whole story. On a turbo diesel, the engine may move the same volume at a given RPM, but the mass of air in that volume can still go up. That is air density, and density is what lets you burn more fuel cleanly, make more power, and improve response. The stock Cummins intake horn and grid-heater layout give away density after the turbocharger and charge air cooler have already built it. We designed the Banks Monster-Ram Intake and Killer Grid Heater Upgrade to keep that density loss down with a freer path, a high-flow intake plate, and an integrated coil-heater approach that preserves cold-start function without the stock grid-heater obstruction. In our testing, the Monster-Ram outflowed the stock elbow and other elbows at the same pressure drop, showing that the head is not the limiting factor people claim it is. Less restriction also means less turbine load and less exhaust backpressure for a given power level, which is why owners feel better throttle response and quicker boost recovery. There is another reason this matters: the factory grid-heater bolt can come loose, go through the engine, and cause catastrophic damage. This upgrade opens the intake path and removes that failure point from the airflow path at the same time.
The video responds to a common claim among 6.7L Cummins owners: that the cylinder head is the engine's airflow bottleneck, so changing the intake elbow or horn cannot meaningfully improve performance.
Gale Banks argues that this confuses volumetric flow with the actual quantity of oxygen reaching the cylinders. His point is not that the head suddenly flows more CFM, but that the density of the air entering the manifold can be improved, increasing the air mass available to the engine even when the head's basic geometry remains unchanged.
Banks explains the issue using the basic four-stroke cycle. A four-stroke engine displaces its full cylinder volume once every two crankshaft revolutions.
At the 6.7L Cummins horsepower peak of 2,800 RPM, the engine displaces about 331 CFM. At roughly 3,400 RPM, that rises to around 400 CFM.
Those numbers do not describe the full intake system, however. Air entering the turbocharger may be flowing at roughly 1,200 CFM while only about 400 CFM reaches the engine because the turbocharger compresses the same air mass into a smaller volume.
That is why Banks argues that mass airflow matters more than raw CFM.
Ambient air entering the compressor is described at roughly 72 pounds per 1,000 cubic feet.
The turbocharger compresses that air, increasing pressure and density while also adding heat. The charge air cooler then removes heat, increasing density further.
Banks describes the turbocharger and charge air cooler as the two components that actually create additional air density. Everything downstream either preserves that density or loses some of it through restriction, pressure drop, poor transitions, or sharp turns.
The design objective is therefore to preserve as much of the density created upstream as possible before the air reaches the intake ports.
Banks tested the intake system using a flow bench configured as a variable mass-flow air pump.
The setup included a bellmouth, MAF sensor, boost tube, throttle body, Monster-Ram, and a billet plate representing the manifold interface. Pressure, temperature, differential pressure, ambient conditions, and mass flow were measured throughout the system.
The goal was not simply to determine the highest CFM number. The team wanted to measure pressure drop, mass flow, and density loss through each intake configuration.
Banks compared the stock system with competing intake elbows, including Shibby and AF designs, as well as the Monster-Ram.
At a pressure drop of 15 inches of water with cold-start heating capability retained, the stock system flowed about 35 lb/min.
The Shibby configuration reportedly lost approximately 3 lb/min when installed with the stock heater plate because of alignment issues. The AF unit reached about 36.5 lb/min, while the Banks Monster-Ram reached 60.9 lb/min.
Banks calculates that as roughly 76% more mass flow than stock at the same pressure drop.
At 20 inches of water, the stock system reached approximately 38.6 lb/min, Shibby about 36.5 lb/min, AF about 41.8 lb/min, and Monster-Ram 72.7 lb/min.
Banks describes that as an 88.3% improvement over stock.
To remove the factory heater as a potential advantage or disadvantage, Banks repeated the testing with a billet plate installed on all configurations.
At 15 inches of water, the stock setup reached approximately 35.1 lb/min. Shibby increased to about 39.5 lb/min, AF reached roughly 44.4 lb/min, and Monster-Ram remained at 60.9 lb/min.
At 20 inches of water, Banks summarizes the improvements over stock as approximately 12% for Shibby, 26% for AF, and 75% for Monster-Ram.
The billet plate improved the competing designs, but Banks says the Monster-Ram still maintained a substantial mass-flow advantage.
The Monster-Ram was designed to do more than simply provide a larger opening. Its job is to diffuse the airflow, turn it approximately 120 degrees, and deliver it into the manifold with more uniform pressure and velocity.
Banks also tested the throttle body by itself. That configuration flowed approximately 59 lb/min, about 42% better than stock.
The surprising result was that the Monster-Ram still performed better than simply allowing the throttle body to discharge freely. Banks interprets this as evidence that the engineered diffusion and turning geometry improve the airflow conditions entering the engine.
The system was also tested at flows approaching 90 lb/min to evaluate higher-output applications.
Banks connects the intake restriction directly to turbocharger workload.
A restrictive intake forces the turbocharger to work harder to deliver the required manifold airflow and boost. That raises turbine drive pressure and increases the pumping work the pistons must perform during the exhaust stroke.
Reducing intake restriction lowers the amount of exhaust energy required to drive the turbocharger. Less crankshaft power is consumed overcoming those pumping losses.
According to Banks, that can produce two benefits: the engine can make the same power with less fuel, or it can make more power at the same fuel rate.
The lower restriction can also improve transient response because the turbocharger requires less shaft speed to support a given engine output.
The final portion shifts from airflow to durability.
Banks argues that replacing the factory grid heater also removes hardware associated with a potentially catastrophic failure mode. The video shows an example where grid-heater hardware entered a cylinder through the intake valve.
The debris damaged the piston and cylinder wall, while other material reportedly continued through the engine and damaged the turbocharger turbine wheel.
Banks uses the example to reinforce the broader case for the Monster-Ram: the cylinder head does not need to flow more CFM for an intake upgrade to matter. Reducing pressure and density losses can increase the air mass actually delivered to the engine, while replacing the factory grid-heater arrangement also removes a failure point from the intake path.
