We present a simple method to increase the conductance of individual template-grown carbon nanotubes contacted with platinum electrodes using a high-bias treatment process which decorates the nanotubes with Pt nanoclusters. The temperature dependence of conductance of the modified carbon nanotubes follows very closely a Luttinger-liquid to Al'tshuler-Aronov anomaly and reveals enhanced number of channels and decreased disorder-density compared to the pristine tubes. Low temperature magnetotransport shows evidence of Rashba spin-orbit coupling, usually absent in bare nanotubes, and a strong suppression of phase coherence at low electronic energies due to electron-electron interactions.