I have upgraded my 2 V8s ('95 and '97) from single to dual exhausts, either with a stock exhaust from a '99 I had lying about or with an SS sportsystem.
First time round was a bit of a puzzle, second one, done just last week, went very smooth.
I needed to add 2 hangers on the LHS, we used bolts mounted in the same place as on the RHS. You also need to cut back the mudflap inside the wheelwell to make room for the hanger (LHS is square whereas RHS has a corner cut out for the hanger).
Biggest problem are the brake lines: on early P38a's they run from each wheel over the axle to the diff and from there upwards. On later models, the brakelines first go to the front of the car.
When switching to dual exhausts, the T-piece between the centre section and both rear mufflers sits above the front of the diff and interferes with the brakeline brackets when the suspension cycles. On the rear of the diff, the panhard rod limits space quite a lot.
I tried to rerout the brake lines under the panhard rod instead of over it, to make sure they could never touch the exhaust, but this puts quite a strain on the lines. So on the second one we tried to route the brake lines between the exhaust and the panhard rod by fabricating some brackets. This seems to work a bit better, but when going offroad I can hear metal touching, so it still needs some tweaking.
I'm seriously thinking about replacing the entire rear brakelines with the newer version (which I have available from my donor car), or have some custom lines made to have a reliable permanent solution.
