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.
