The effects of stress-induced martensite aging (SIM-aging) along the [110]B2-direction on the thermoelastic martensitic transformation in Ni49Fe18Ga27Co6 single crystals were investigated. It was experimentally established that the effective regime of SIM-aging (at T = 423 K, 1 h under a compressive stress 450 MPa) results in a stabilization of stress-induced martensite and inducing the tensile two-way shape memory effect with reversible strain of +9.0 (± 0.3) % along the [001]B2-direction which is the perpendicular to the SIM-aging axis. Maximum work output of Wmax = 0.14 J/g (1125 kJ/m3) that can be realized using the two-way shape memory effect was obtained.