After 4 years sitting in a garage my Golf is finally back on the road.  It passed it's MOT yesterday  

But.......... I've got problems with the zorst.  It's a Mongoose full stainless system and it gets really really hot.  Even with small bumpers the heat destroyed the back bumper, fried to a crisp above the tailpipes.  I have now changed to big bumpers and to stop the same thing happening I got rid of the DTM tailpipes and re hung the exhaust a bit lower (it now bangs on the back axle when the car is fully loaded).  I though all was well until today.  Had the car out for a proper thrash and when I came back the bumper is fairly well melted.  I'll post some pics in the gallery but does anyone have any ideas how to stop this ?
or why does my exhaust get soooooo hot ?  The engine temp is normal and the oil sits about 94 - 100.