Histogram of the collision velocity, v_coll, for giant impacts occurring in all the 109 000 unstable compact systems. v_coll is expressed in units of the mutual escape velocity of the colliding bodies, v_esc (Equation 2). We find that only 8% of collision occur at v_coll > 2v_esc, for which our simplifying assumption that all debris produced by giant impacts are reaccreted by the target can artificially lower the mantle stripping efficiency (Section 2.2.3). Our results are therefore robust against this assumption.