I haven't found Astia to exaggerate colour in my personal opinion, but I find it to still reproduce the richness of a brilliant sunset.
I have yet to take a colour negative sunset image that hasn't had a loss of colour and shifted or inserted colours that dont seem correctable as it throws the rest of the image out of whack doing so, Ektacolor 160 (Portra?) and Reala was the absolute worst for this I've encountered, other films doing much better, regardless if it's been scanned or printed.
Ektacolor took post-sunset purple sky and pink clouds, and made them into a simply dull, overcast sky, dull pale blue and grey clouds. While I didn't try optically printing it, I couldn't correct it or get the slightest hint of colour from it.
The negative is only an in-between product.
The best results I have, have had muted colour, and is flat, it lacks the original vibrance of the scene, which I can capture with digital or E-6.
I generally try exposing the highlights as midtones, ie: spot metering them, and taking that as my exposure, rather than adjusting them up to highlights like I would on digital or E-6.
If you could suggest a method of best reproducing sunset on a C-41 film, I'll try it. I would like to be able to do that, even better if it doesn't involve underexposing.