Lots of good points which I agree with. Not everyone will pay, but a few will, and it won't take much on a small batch order.
Remember exhaust takes the first hit on a tip over. It is a much higher turnover piece on a bike than a shock, forks, etc.
I think if 10-15 sets of full systems came to the US, they'd sell.
First, there are almost no SP1 systems, so this would fit that market nicely.
2nd, some people like full systems, and there is almost nothing available in this arena. One does have the less expensive Hindle and the expensive ladybird HRC replica. Nothing in the middle.
There is a core group of people who want nice stuff. That is why sato's are commanding high used prices, Ladybirds are selling, etc.