Pitjantjatjara is an Australian language with five stop places of articulation /p t t c k/ in three vowel contexts /a i u/. We present word-medial stop burst data from nine speakers, examining duration, formant, spectral moment and spectral tilt measures. Our particular focus is on the apical contrast (alveolar /t/ vs. retroflex /t/) and on the alveo-palatal /c/ vs. velar /k/ contrast. We observe differences between the palatal and the velar depending on vowel context, and we discuss the possible aerodynamic and acoustic sources for these differences. By contrast, we find that differences between the alveolar and the retroflex are minimal in all three vowel contexts. Unexpectedly, in the context of /i/, various spectral measures suggest that the articulatory release for the retroflex /t/ is in fact more anterior than the release for the alveolar /t/ - we discuss this result in terms of possible articulatory overshoot of the target for /t/ before /i/, and suggest that this result provides additional explanation for the cross-linguistic rarity of retroflexes in an /i/ vowel context.