Request Allowance to Remove Catalytic Converter
#39550 from Richard Hromin · Taken care of · Minutes (2026-06 Fastrack)
The committee discussed this topic intensely over the past months. Not only within the context of sunsetting the OBX header for
the 07-10 Mini Cooper/Clubman, but also regarding the category as a whole.
We considered as many avenues as we could, which culminated in the decision to approve specific aftermarket replacement
catalysts/exhaust manifolds for each platform. Our rationale for arriving at that decision was as follows:
1. It was the best avenue available to maintain our current BOP
2. It provided parts availability to replace OEM parts that are becoming unavailable
3. Specifying a specific brand and part number is a solution tech can enforce
As these vehicles age, availability of certain parts is going to become an issue. We are already experiencing this phenomenon
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with suspension kits, as several Bilstein B14 kits have become difficult or impossible to acquire.
This is also the case with OEM catalysts/exhaust manifolds. For example, the OEM catalyst for the 07-08 Fit is no longer available
from Honda. Additionally, many of these OEM cats/manifolds are cost prohibitive to purchase. An OEM replacement manifold
for a Sonic is over $2,000 plus a core charge. That does not fit the cost-controlled philosophy of B-Spec.
Requiring OEM manifolds made sense with B-Spec was a pro category, as many of these cars were brand new and still in
production. However, this is no longer the case. Allowing an aftermarket replacement version of the OEM parts was a logical
evolution.
The committee did consider allowing the removal of catalyst material from stock manifolds. However, this solution posed
several challenges in terms of tech enforcement, maintaining current BOP, and differences in exhaust configurations within the
category.
There are several catalyst configurations within the category. For example, the Yaris, 1st-generation Fit, and Versa all feature cast
manifolds with a separate primary catalyst.
However, the Sonic, 2nd/3rd-genration Fit, Fiesta, Rio, Accent, Mazda and Mini all have a catalyst that is integrated into the
exhaust manifold. The 2G/3G Fits specifically have a manifold that is a single runner design as the cylinder head features a single
exhaust port.
Due to the variety of exhaust configurations in the category, there was not a one size fits all solution. In most cases, removing
the catalyst material from the manifolds would have required cutting the unit itself open and then re-welding it back together.
For a category that is largely based around bolt-on catalog parts, this solution did not fit class philosophy.
Allowing the removal of catalyst material would have also potentially resulted in a wide-scale BOP change. Which the committee
was not in favor of. That said, we did make specific allowances for the Versa and Yaris to remove their catalysts as they are a
separate unit from the manifold. These were two platforms that appeared to need BOP help. The 1st-generation Fit was already
permitted this allowance last year.
Additionally, we have already made positive BOP adjustments to the Mini in anticipation of the expiration of the OBX header
and will continue to do so if data points to additional changes being needed. Further changes will likely focus on additional
weight reduction, as many of these cars are still racing with over 100# of ballast, but plate changes would also still be
considered.
The expiration of the OBX header leaves the Mazda 2 as the sole platform with an approved aftermarket header in the category.
Thankfully, that part is provided by a direct stakeholder in the series that can guarantee its availability. Which was ultimately not
the case for the supplier of the OBX header than had been approved for the Mini.
Ultimately, our goal as a committee is to provide a ruleset that is fair and cost effective. While there is ultimately only so much
control we have over OEM and aftermarket parts availability, we will continue to do our best to ensure that this does not
become a limiting factor to the category’s growth or BOP management.