Evidence for EHV emission in CH₃OH and H₂CO towards the L1448 outflow, together with possible detections in HCO⁺, CS, and HCN. The black histograms represent the data and the red histograms are scaled-down SO(3₂ − 2₁) spectra to illustrate the expected location of the EHV peak (near V_LSR = 70 km s^-1 in L1448 and near  − 35 km s^-1 in I04166). For CH₃OH and HCN, the red histogram is a synthetic spectrum derived using the SO(3₂ − 2₁) line as a template (see Appendix C for further details). Note the weak EHV peaks and the gradual transition from well defined secondary components in CH₃OH and H₂CO to more wing-like features in HCO⁺, CS, and HCN. Several unrelated lines are indicated, and the horizontal lines in the CH₃OH(3_k − 2_k) spectra mark the position of weak k = 2 components that may contaminate the EHV feature in I04166. See text for a discussion of the reliability of each detection. SO was chosen as a template due to its similar behavior to CO and higher sensitivity to dense gas.