My dad had one made for his xr4i(4L V8), first time he gave it a bit of grief the prop tube twisted like a soft chew and snapped clean in two, had it not been for the bar supporting the exhaust it would possibly have dug in the ground and launched the car in the air, like my mates 3L capri when the joint broke, it was so funny, no one hurt thank god.
His was made by a company no longer in existence, called powertec brookes.
tabetha