Do not go gentle.

Do not go gentle.

"In this Special Series, I document my CSL airbox experiences. I take you into my unboxing of my various airboxes, the hardware checklist, the tuning dilemma, installation notes and my driving impressions with proper sound clips.

In this entry, I document my DIY installation of the CSL airbox in details. I look back at the long checklist of hardware along with the expensive and egregious things needed to successfully install a CSL airbox."

A quick look back. 

Hardware review. 

The CSL airbox on its own is usually 40 to 60% of the planned budget that should be planned for a complete installation. The costs will vary depending on which brand you opted for, along with aftermarket or Genuine BMW installation hardware, and if you do the MAP conversion. 

Before getting into it, I suggest you review the hardware checklist and its options to installing a CSL airbox.

On this 2nd CSL airbox installation, I opted for a hardware kit that was a bit closer OEM specifications by using the Genuine BMW ITB and trumpet clamps. 

I kept it aftermarket on the boots and opted for Turner's silicone boots over the Genuine BMW's rubber material. Silicone lasts forever and do not degrade. 

My original installation of the Frozen airbox was using worm style clamps, but every other hoses were Genuine BMW and original CSL parts. 

The MAP equation. 

For pre LCI S54s, upgrading to MAP is an expensive proposition - I feel it's worth it. For LCI S54s, the MAP conversion is an inexpensive no brainer. 

documented the AlphaN versus MAP dilemma here and curated the MAP conversion kit here

My previous installation also required a new MSS54HP DME to support the MAP conversion like the original CSL. 

The MAP conversion involves some rewiring into the MSS54HP DME. I had this professionally done. 

The dip stick. 

The CSL airbox installation will require the relocation of the OEM dipstick by modifying its bend or the use of the OEM CSL dipstick. It's part of my hardware checklist

We bent the OEM dip stick on my previous installation. 

My DIY installation.

Considering the look-back, my DIY installation is a partial installation. I filmed and edited a 90s trailer / reel on instagram here



#1: Split the box. 

CSL airboxes are usually delivered assembled. The number 1 step is to unbolt the two sections from one another to work the trumpet section of the airbox on the shelf. 

4x bolts hold the section together at the top. The lower section is guided by 2x pins.  

#2: Slide in boots. 

With the trumpet section on the shelf, I slid in the silicone boots. I didn't have to apply lithium grease - but it could be useful if you don't feel like having to apply force on your 2,000$ + carbon airbox. 

The boots have a direction dictated by the inner wall design. This helps you intuitively understand when to stop pushing.  

#3: !&@? them clamps. 

The next step is e·gre·gious. 

A lot is made about how aftermarket worm-style clamps can potentially obstruct the individual throttle body actuator operations and the purists will tell you they look ugly. 

They aren't wrong, but not enough is made about the one time use predicament of these clamps and how counter-intuitive the Genuine BMW units are to install. 

The clamps are slotted by the 2nd clamp' tooth before the protruding metal section is compressed using a set of clamps. Having a 2nd pair of hands will help. 

You'll understand this is a one-way street. Considering this, I only installed the boot clamps until the installation is final.  

I aligned the protruding metal section at 30 degrees towards the firewall. The Original CSL had them hidden out of sight.

#4 Clipping in sensors & hoses. 

The MSS54 uses a myriad of sensors and hoses to properly operate its air intake tract before and after the air is filtered.

A properly designed CSL airbox will have the required bungs to clip in all hoses, sensors and brackets. I touch on the IAT relocation kit and sensor later on. 


This vacuum hose is 1 of 3 that will be bolted underneath the box. 

It gets clipped into this bung, as seen here from within the airbox. 

This smaller hose is trickier to clip in but once it's in, you can feel confident it is without even seeing it.  

its bung is located further out by the firewall, as seen here from within the airbox. 

This is the air shut off valve. It is an original CSL part. 

It gets clipped in at the top of the airbox. 

This crankcase ventilation hose is another CSL specific part. I don't have the valve covers on here to better showcase exactly where it is clipped into the engine. 

If your CSL airbox's boots are misfitted, this is where it'll show. You won't reach out far enough to clip it in. 

Those with a keen eye will notice I am missing the bracket SKU 11617831740 - this is a collateral mishaps from the previous owner's Supercharger installation that required its removal.

The bracket bolts into the airbox for a sturdy fitment. I will probably revisit this. I also did not finalize the 2x hoses sliding into the airbox brackets by firewall. 

#4 Filter slide-in. 

I re-used the Genuine BMW filter from my original installation. This is a part of the install you need to be careful attention as a mis-installation can lead to dust making its way into the airbox - unfiltered.  

The filter has black "pads" located across the outer edge of the red frame to properly seal in the filter against the carbon wall. 

The filter is oiled and is made by BMC. 

The CSL airbox by HaimusRacing has alignment and guiding tabs by the firewall to properly position the filter. 

This new CSL airbox had its mold revised from my former Frozen airbox for better filter fitment. 

These will require some adjustments as they are somewhat flexible - and the carbon isn't! I ran my fingers across the outer edge to ensure proper fitment was achieved.

#5 Align, pin & bolt the box (and plug in the IAT!).

It's now time to join together the two sections of the CSL airbox. Most properly designed airboxes will have 2x guide pins ala OEM by the lower edge of the trumpet section.

They should go through the holes that are aligned on the outer section of the airbox.  On the picture below, you can see the IAT sensor protruding through its bung and the one of the guide pins (slightly blurred!). 

You'll notice the IAT sensor is positioned further forward than on other CSL airboxes. It's a proven design feature to reduce heat soak in heat temperature environments. 

When the pins are through, bolt in the 4x bolts at the top. Do not thread all the way in until all 4x bolts are in. 

Tadam! The black bolts are a nice touch of the Shadowline airbox. 


#6 The Tuba

The optional ABS, 3D printed snorkel is a design I personally adore. It's inexpensive, looks OEM'ish and is rugged. I feel it's a must have for anyone running the OEM bumper or the CSL 1:1 replica.  

Before you begin, I suggest you have your undertray off to perform the installation, just in case you drop the hardware.    

This snorkel exclusively fits the HaimusRacing airbox. 

The snorkel fits through the chassis, behind the headlights. It's missing the Original CSL air duct that feeds into the signature hole on the bumper. 

The snorkel is bolted in using 4x sleeved bolts, nuts and washers. 

3x of them are relatively easy to assemble and bolt, while the other sitting fully underneath the snorkel is a PITA and needs to be done blind.

Some may question its usefulness. The original unit was supposedly, mostly for meeting maximum decibel outputs required by TUV/EC legislations. 

Without the flap, its use are diluted cold air feed, and aeshetics.


AH! Looks great doesn't it? I am mostly a fan of satin finishes for carbon intake systems but this is a design that needs to be gloss. The complex curvatures of the airbox and the signature aesthetics deserve to pop. 

My engine bay was also fully resprayed and clear coated in high gloss. It complements the airbox. 

I didn't clamp the ITBs yet as I may need access to the power steering reservoir to fit an aftermarket unit before re-assembly. 

I do not look forward to having to do these clamps with the airbox in the engine bay. 

Up next: we finish up the car and the CSL airbox install. 

We go around the block, flush the oil, and hit the dyno before final sound clips. 

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