[PNJSNAK]

Here is what I did:

First I have a 351W.
I installed the headers and sise pipes with the reducer pieces.
I used a 4x4 to space the side pipes away from the side frame rails. I leveled the side pipes parallel to the side frame rails.
I used 1"x1" x 1" long pieces of angle iron that were welded to the side pipes. I created a bracket that mounts to the under side of the frame side rails. I mounted this bracket about halfway down the frame side rail.
Once in position I welded the reducers to the headers.
I like the way Tony welded brackets on the header and side pipe. You can bolt them together or use springs like on a motorcross engine downpipe.
Unfortuneately I simply used stainless steel sheet metal screws in each pipe, it is okay but I really like what Tony did.
Bye the way the 4x4 spaces the side pipes about 3/4" to an 1" from the side of the body when mounted.
Hope this helps, just what I did and it looks great see pics in my gallery.
Jim