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
Sharpen the soundtrack of your BMW M135i (F20/F21) with this Milltek Sport Non-Resonated Cat-Back Road Exhaust System. Removing the factory resonator gives this system a louder, more characterful tone that brings out the best of the turbocharged six-cylinder. Available in three tip finishes and designed as a bolt-on fitment, this system is the ideal first performance exhaust upgrade for the F20/F21 M135i.
Road-friendly in character but with noticeably more sound presence than the OEM system, this cat-back is well suited to daily driving as well as spirited use. No ECU remapping is required. Manufactured from 304L stainless steel at Milltek Sport's UK factory.
Fitment: BMW M135i F20 & F21 (Non xDrive models)
E-marked: EC approved
Tip options: Polished (SSXBM964), Cerakote Black (SSXBM965), Titanium (SSXBM1023)
