String Theory Garage will be closed to the public from Wednesday, 29th July to Thursday, 6th August for our annual shutdown.
If you need to get in touch, please leave us a voicemail or send an email. Our team will happily get back to you when we return on Friday, 7th August.
Shopping online? Don't worry! Our online store will remain active! We hope to ship orders placed for in-stock items as normal during the shutdown. Anything else will be dealt with upon our return.
Thank you for your understanding, String Theory Garage Team
Unlock a louder, more aggressive exhaust note on your BMW M140i (F20/F21 LCI, OPF/GPF) with this Milltek Sport Non-Resonated OPF-Back Exhaust System. Engineered specifically for OPF-equipped LCI models, this non-resonated system maximises exhaust character from the OPF outlet rearwards — delivering a more uninhibited, performance-focused exhaust sound that's a significant step up from the OEM system.
Without the factory resonator to mute the exhaust note, this system produces a more dramatic tone that makes the most of the B58-engined M140i's character. Available in five tip finishes and designed as a straightforward OEM replacement — no cutting, welding, or ECU remapping required. Manufactured from 304L stainless steel in the UK.
Fitment: BMW M140i F20 & F21 LCI (OPF/GPF equipped models)
Race product: Yes
Tip options: Polished, Cerakote Black, Titanium, Burnt Titanium, Carbon Fibre
