GSI will replace the Wideroe prestripper linac by an RFQ and IH-type accelerator presently under construction. The new prestripper linac should deliver beam intensities to fill up the heavy ion synchrotron SIS to the space charge limits for all ions. In case of uranium the new injector has to deliver 15 emA U. One of the two existing ion-source terminals has already been rebuilt for installation of the high current sources of CHORDISand MEVVA-type. Therefore, investigations of high-current beam transport have been made in the existing LEBT. For that, additional beam diagnostic elements have been installed: beam transformers, emittance measurement devices, residual gas ion spectrometer. The measured beam properties, e.g. transverse emittance, degree of space charge compensation, support the design of the future LEBT. According to the various requirements two layouts of the new LEBT have been studied so far.