I'm not sure why folks don't find a local exhaust manufacturer and get them to make up a bespoke system? If I'd kept my car, that is exactly what I was going to do, using some straight through absorbent silencers, and maybe a little fishtail/Brooklands style pipe aft of the silencer. I'm sure it won't cost any more than MMC are likely to sell them for,substantially less, I suspect.
This is exactly the approach I was going to take Paul and in fact had identified and spoken to two such outfits who were only too willing to make the custom pipes as I had imagined them. Only hassle was getting my car to them and leaving it there for potentially a few weeks as they sorted out the build. So it was all a good idea, just waiting for me to deal with the logistics and timing....
..... during which the G56 chaps came up with the same idea and did all the hard work themselves! Which is why I am keen to see one in the flesh and hear more about it.