"fifty" and "sixty".

Is the [t] in these words aspirated or not? I've been aspirating it, but I'll stop if it's wrong.

I don't seem to aspirate them judging by measuring my breath with my hand... I can't hear a difference between aspirated and unaspirated so that's the only way I can tell.

They're not aspirated here, normally being ["fIfti:] or ["fIt:i:] and ["sIksti:] or ["sIksi:] here.

They're not aspirated in my speech: ["fIfti], ["sIksti]. I think this would hold true in most dialects.