Try JP Exhausts in Congleton https://www.jpexhausts.co.uk/
Really know what they're doing.
They had done a delete on my current zed for the previous owner before I bought the car. I hated it, so went to them with a DLV modded back box I had from my previous zed, and they reversed the process. Not cheap, but as they created a flange type of connection I now have the choice of swapping between the delete and the back box whenever I might like. (Which will be never, as the delete is just awful and intolerably loud. Don't do it).