that's saves money, because eBay prices ....1st, the engineer who decided to use galvanized bolts on the stainless steel exhaust of the E32 should know that after 10 years, the galvanization is gone and the steel is melted,making it impossible to unbolt them
Here is your best friend to remove the previous exhaust: a dremel!!!!!

Cut the bolts and get ready for some serious hammering ....
The E38 exhaust system has the same dimensions, except the back hole of the exhaust system
So, you ll have to do some welding ...
Cut the E32 exhaust CAT exit:

then, weld the removed part on the E38 CAT. The lenght of the Cat is right, so, don't forget to cut a little the E38 cat, to fit properly.

As you can see, the front fit perfectly!
Next posting ... the swap will be done, and ready for the Turbo exhaust too!