"These build journal entries are part of a Special Series on the S85 OE+ Carbon Plenums and OE+ Carbon Side Intakes (M5/6 V10).

In this entry, I document the newly developed OE+ Carbon Side Intake Lids (M5/6 V10) and its features to improve engine bay aesthetics and induction sounds within the OE+ philosophy."
- Matt

A needed development.

Since documenting the S85 OE+ carbon plenums in 2022, the S85 and M5/6 V10 platforms saw the introduction of new carbon plenum options from Eventuri and InfinityDesign.

Both brands sought to compliment their well established side intakes along with updating their designs. They each opted for reverse cone filters which influenced design to create vastly different aesthetics to the original air filter boxes. 

Complete plenum and intake kits from these household brands have set prices starting at approximately 4,500 USD. Additional expenses are required for badges and AlphaN tuning specifically on the CSL 1 piece plenums. 

The legacy side intake option from Dinan now retails for 2,250 USD. It uses plastic construction with carbon lids. From my perspective, the value proposition is lower than it used to be

With the OE+ S85 carbon plenums priced below 2,000 USD, I felt there was an opportunity in the market to expand upon the OE+ philosophy of the plenums onto the side intakes to deliver a quality product that would be priced below complete carbon kits. 

To learn more about the OE+ carbon plenums, read the previous entry here.

The OE+ philosophy. 

We begun development of the side intakes in 2025 with the first prototypes produced by Fall and road tested. In January 2026, the first production unit for was received for Richard, a customer who previously purchased the OE+ carbon plenums. It was used in pictures below to document. 

Our intention was to implement the same fundamental design elements of the OE+ carbon plenums: we would replace the original plastic lids with complete pre-preg carbon units and seek to retain the original shape of the intakes. We would integrate the original baseframe and lower section to ensure OEM fitment, reliability and serviceability. 

1:1 design. 

The production side intakes retain the original shape with slight design improvements to smoothen the aesthetics. The original plastic units have ridges on the sides - those were removed across the entire design. 

The lid is made for pre-preg carbon fiber cured in autoclave. Here, we used 2x2 weave pattern that matches BMW Performance carbon components along with matte clear coat. You can also select 1x1 weave as on the CSL and E92 M3 carbon roof panels and high gloss clear coat. 

The weave pattern is carefully laid into the molds for optical alignement with the OE+ carbon plenums: the left bank aims at 10 o'clock and the right bank aims at 2 o'clock. The end results are subtle, yet premium aesthetics. 

1:1 trumpet design. 

The side intakes were flow optimized by BMW M. In addition to being fully sealed, the original lids featured a bell mouthed trumpet optimized for performance. This design is re-created in carbon in our design. 

All original features. 

The carbon lids were designed with all original functional features and manufactured in pre-preg carbon. 

The right side intake lid notably includes the brackets for the coolant hoses and the washer fluid reservoir bracket for its filler pipe. The left side intake integrates the original Secondary Air Pump (SAP) bung to connect its hose.

Both intakes integrate the MAF sensor bungs. They do not have threaded inserts as to re-use the original screws. If you plan on deleting SAP and using AlphaN tuning with IAT sensors, we can manufacture the lids without these bungs for a seamless design. 

Original baseframes.

The OE+ philosophy mandates using the original underpinnings of the intakes. As with the plenums, we opted to source used side intakes that we dismantle and refurbish.

During the manufacturing process, carbon lids are merged with the baseframes with high strength, high temperature 2 component adhesives to ensure reliability. 

We do not 3D print the plastic bases. This is most critical as the basefames incorporate functional features such as the air filter channels and tabs that are key to achieving a complete seal of the intake to maximize performance and filtration. 

Ease of installation.

BMW designed the original lids and its baseframe in part for ease of servicing. Most if not all engine related services will require to remove the complete side intakes from the engine bay. 

The original lids use metal clips to lock with the lower section. This mechanism is fully retained by using the original baseframes. It takes a few minutes to uninstall and install the lids - with all tabs being perfectly aligned with the metal clips. 

How it improves induction sound. 

Thinner lid. 

The main benefit to using carbon lids is to improve induction sounds of the S85. This is achieved through the carbon material properties.

For this use case, we maximize carbon's higher tensile strength to achieve a reduction in the thickness of the lid to maximize sound. As a collateral and margin benefit, it leads to a slight reduction in weight of 0.35 lbs / 0.16 kg. 

Charcoal filter delete. 

Specifically for North American owners, our original side intake lids were fitted with emission reduction devices known as charcoal filters. They are used to trap fuel vapors.

As a side effect, they also reduce decibel output of your side intakes. Our baseframes are delivered without the charcoal filter. If you require them for emissions testing, they can be installed onto the baseframe as well. 

Aftermarket filters. 

To further increase induction noises, you can also compliment the carbon lids with any OE replacement aftermarket filters such as BMC, K&N or AFE.

They most often oiled instead of dry, allowing a reduction in filtration material and an increase in sound. They also tend to increase the filtration area by improving the design of the filter. When combined with removing the charcoal filter, there will be an increase in horsepower and torque of your S85 of +/- 10whp. 

Lids versus Plenums. 

Richard initially installed the OE+ carbon plenums and subsequently added the OE+ carbon lids along with BMC filters without charcoal filters. He immediately noticed the additional decibel outputs from the intake system. His comments are below. 

"I just drove it. Induction noise is much louder than with just the OE+ carbon plenums. The noise is intoxicating; coasting around 6,000 RM in 2nd gear and then flooring it makes an induction bark that's so loud. I love it."

BMW M put a considerable development into this engine and its sealed intake system. 

Through our OE+ philosophy, we achieved our goals of improving aesthetics and induction sounds at an reasonable price.