Ok, today we started cutting the extra exhaust I bought.. here are some pics. Enjoy!
We followed the sections hoping to find a design similar to the Dinan sketch. Just below the numbers that are stamped on the exhaust there is the location of the Helmholtz chamber. It is totally sealed from the rest of the exhaust.
Obligatory awesome sparks picture.
We were able to bend back the cover, saving some welding work and keeping it as stock-looking as possible from the rear once installed.
Peeling back the cover, it looks like the diagram in the earlier post is pretty close to reality. We will tap off that top pipe about halfway into the bend to the left and shoot it down towards the lower corner, exiting out the side. We will roughly need a 90deg bend and a straight section on exit.
Note the double walls - is this for sound deadening and heat? Maybe this contributes to that raspy sound? We'll have to spot weld these back together later before welding the cover back on.
Both sides open - will have to open the bottoms too later to be able to weld.
The 2.5" pipe inside splits into what looks like dual 2" pipes before exiting. Note that the pipes are not totally welded, just sort of shoved in and spot welded. Kind of weird. I guess it doenst matter if exhaust gases enter this area. If you look to the right, you can just start to make out some packing material peeking out. The sound absorbing center section of the muffler is not sealed. It looks like the packing material is made of straight lengths of very thin metal strands.
The new plan is to come out pretty close to my original plan, but farther towards the rear and the pipes will be at a slight angle rearward. Now I have to order the 2.5" valves and line everything up. Stay tuned!