It should be just --alt-preset extreme
Have no idea what the "/ q 0" is...but it is unnecessary.
Using standard will reduce file size a bit, yet still maintain high quality. Extreme may do better on harder to encode material.
10-27
edit: From switches.html
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* -q 0..9 algorithm quality selection
Bitrate is of course the main influence on quality. The higher the bitrate, the higher the quality. But for a given bitrate, we have a choice of algorithms to determine the best scalefactors and huffman encoding (noise shaping).
-q 0: use slowest & best possible version of all algorithms. -q 0 and -q 1 are slow and may not produce significantly higher quality.
-q 2: recommended. Same as -h.
-q 5: default value. Good speed, reasonable quality.
-q 7: same as -f. Very fast, ok quality. (psycho acoustics are used for pre-echo & M/S, but no noise shaping is done.
-q 9: disables almost all algorithms including psy-model. poor quality
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There is no point in using -q x with the presets...they already include the optimal value