330 Cap on Supply Quality

If you put a Quality prod higher than 330 in a corp as a supply, it drops it down to 330.
In other words if you have an item than cannot be built on your planet, but the only available is Q600, it will be dropped to 330 as soon as it is added as a supply. So you do not even get the effect of raising the qaulity of the average of the rest of the supplies.

Don't purchase supplies at such a high quality levels. It is a waste of money.
corporations will not have a benefit. The best quality for corporations is around 200.

such high quality cannot be produced.

Only weapons and ammunition can be upgraded and their quality makes sense when army units can fight at very high quality levels.

I keep mine at 170, should I increase to 200?

I think it will be better.
we are trying to make more sense of higher quality and currently, 200 will get you positive returns.

you can increase to 180 and see if there is an improvement. It is not easy to see as there are many parameters influencing profits.