E34 Exhaust

I have an E34 with a single tail pipe, I want a double one, I don't want to fit a whole new exhaust system or a new rear box. So is there a double tail pipe I can fix to the one that is on there now. Without having to cut too much of the tail pipe as there is only about 6 inches before the rear box. Also most I see are too long so they would stick out to far and I can't seem to find any wide enough to fit over the tail pipe. I am in the United Kingdom. Thanks.