This Resonator delete pipe replaces the mid resonator (second silencer after the flex section).
 This will be the Round Resonator approx 20" length. Suitable for OEM and MPE exhausts

118i F21 Mod - Resonator Delete pipe 

Fitting guide:

Cut the round resonator immediately before/after the welds on each side

Slide the res delete pipe over the existing pipework by approx 50mm per side and clamp into place 

As simple as that

please see listing images for reference.