Description
NEW 2026 PRODUCT!
FINISHED/TESTED TO ORDER 1-2 DAYS DISPATCH!
NEW VERSION – Brand New Highest Quality German Made Units – Spec is equal to If not higher quality than the Original OEM! Unlike Budget Copies that have a completely different internal layout & components that can fail in a short time period. These follow the OEMs Design in function & components.
With OEM throttle bodies for the MINI Cooper S Gen 1 now long discontinued, we set out to engineer a true long-term solution rather than rely on compromised alternatives. After extensive and costly research & development, it became clear that many aftermarket pattern parts simply weren’t up to standard. Our new GTT 63mm BIG BORE Throttle Bodies have put an end to modified second-hand units, other brands may still offer this option, however they have approx. 20 year old internals including the gears and motors! .
Restrictive intake?
Because the throttle body sits before the supercharger, it directly affects how easily the supercharger can draw in air. The goal is to minimise restriction ahead of the charger so it can operate as efficiently as possible & increase spool up.
As the supercharger inlet & the black plastic pipe (TB to SC ) has a larger cross-sectional area than the standard 57mm throttle body, the throttle body itself is still a primary restriction point. Increasing its bore size reduces pressure drop at the entry point, allowing the supercharger to ingest air with less effort.
Lower restriction means:
Reduced inlet vacuum before the charger.
Lower intake temperatures under load.
Less parasitic effort required to move air.
Improved boost response and efficiency.
In simple terms, the supercharger doesn’t have to “work as hard” to achieve the same or greater airflow. (A restrictive air filter, intake hosing, throttle body etc. will increase intake temps)
There’s also a drivability benefit. A larger throttle body flows more air at a given butterfly angle. That means for the same pedal input, the engine responds more sharply. It creates a more immediate, sportier feel, similar to how the R56’s Sport mode changes the throttle mapping to open the butterfly further for a given pedal position.
So it’s not just about peak power numbers. It’s about reducing restriction, improving efficiency, helping the charger spool more freely, and sharpening throttle response.
Why 63mm? Not 64mm?
Through extensive testing, we’ve found that 63mm is the optimal size for performance on this platform.
We trialled several 64mm throttle bodies from VW Golf and BMW applications. Although they physically fit and initially appeared to function correctly, they proved unreliable in everyday use. Cars would randomly cut out, enter limp mode, or trigger fault codes relating to throttle body faults or suspected air leaks.
To properly validate this, as a further test we also produced R53 throttle bodies in 64mm and 65mm sizes. While both flowed more air in theory, real-world results showed intermittent operation and inconsistent behaviour. Neither provided a dependable long-term solution.
If we could sell and market even larger than 63mm throttle bodies….. We would! (That’s why no other brands copying our GTT units haven’t either for the very same reason)
If we could offer reliable larger units from other vehicles without all the extensive work that go into these r53 units… We would!
After testing across multiple vehicles and conditions, 63mm delivers the best overall balance of:
Increased airflow with reduced restriction.
Stable ECU control and throttle adaptation
Consistent drivability.
Long term reliability without limp mode issues.
Increasing size beyond 63mm introduces control and calibration challenges that outweigh the airflow gains. At 63mm, performance is improved while maintaining proper system integration and OEM-like reliability, which is ultimately what matters most. The car ‘thinks’ there is a throttle body error or air leak’ due to excessive engine speed at the throttle bodies idle position (in particular) but also for a butterfly angle throughout the rev range.
New for 2026 !
These units are 100% brand new, not refurbished, not 2nd hand rew-worked and no longer supplied on an exchange basis!. That means no surcharges, no core returns, and no downtime waiting to send in your original throttle body. While priced slightly higher than the old exchange versions, you’re investing in a premium, brand-new component that delivers superior quality, reliability, and a clean, factory-fresh finish.
The original 63mm TB design.
GTT are the original designers and manufacturers of the Gen 1 MINI 63mm Big Bore Throttle Bodies. Our throttle bodies have been proven in real-world use for over 20 years, delivering consistent performance, reliability, and longevity. While others have attempted to replicate our design and quality, none have matched the standards we set. We have made an evolutionary step with this Brand New version while other companies will continue sell reworked or exchanged 20+ year-old units with unknown internal wear, often at inflated prices that include costly surcharges. In these cases, you’re effectively paying for machining on an old throttle body—sometimes receiving an exchange unit in worse condition, with reduced lifespan. Our throttle body is brand new, purpose-built, and engineered to perform as intended from day one.
The Standard 57mm throttle body when modifying to higher levels of power becomes a restriction that needs to be removed. Consider also that at wide open throttle the excessively wide butterfly spindle imposes a further restriction (a reduction of 570 square mm’s) reducing the cross sectional area to the equivalent of just 50mm diameter! At GTT we precision bore to 63mm diameter. This size perfectly matches the internal diameter of the SC inlet plenum which it is bolted and dowelled onto. The surface finish is maintained to CLA 32 or better. In other words very fine and accurate, ensuring no sticking throttle plate or leaking on idle. We have seen other offerings that would make a ploughed field look flat! Throttle bodies are sold on exchange. Where possible the customers own part is modified. .
Fitment: MINI Gen 1 Cooper S (also JCW / GP1)
(Fits all gen 1 MINI Supercharged models…. Cooper S, JCW & GP1)
£449+vat OUTRIGHT PRICE… NOT ON EXCHANGE! ( No need to pay a Surcharge or need to send us your original unit as part of the old exchange basis)
LOT OF WORK GOES INTO MAKING THESE COMPLEX ITEMS, There maybe a few small light marks from the work…. You cannot see the unit when installed, you will not be disappointed by the performance!
The car will calibrate the TB automatically after a minute of full operation (rev the car / drive it) Note: the car usually idles strangely on initial start up.
