I'm just having more fun than should be legal and it probably isn't if I
look far enough into the County, State and Federal statues, but I am
never-the-less. I have pretty much followed the Cafe numbers for header
length and the 4-into-one collector. Keeping in mind friendship to my
neighbors, I also included a muffler. I purchased the collector and
muffler from Barnes Stainless and will be purchasing the header tubing,
321SS from the same source in all likelyhood. A/C Spruce has the tubing
listed at $8.75/ft.
I've made up some PVC headers complete with flanges glued on and am
heating the PVC with a heat gun and bending them until I get the pipes
where I want them. The plan then is to take the bent up PVC to a muffler
shop that has a mandrel tube bender and have them bend up the expensive
321 SS tubing. I plan on welding in some of the 3-bolt ball fittings to
both ease the stresses and make installation and removal easier.
My plan is to install the stock exhaust, do a hover and check the MP and
then quickly change exhaust systems and repeat. I'm hoping to see a MP
improvement.
I've had this plan in my "Round Toit" list every since I read the Cafe
study.

Dang I sure do like the experimental category. No bureacrats in the way.
Stu
Well the heating of the PVC wasn't working as well as I hoped so I changed
to using PVC elbows. I modified some 45° elbows by cutting out a wedge
fron the outside of the elbow and reduced the angle to 30°. I had to
drill a couple of holes and use some safety wire to hold the elbow to the
30°. I also turned the PVC pipe ends in the lathe to make them turn a bit
easier in the elbows. Needless to say it is a projet in progress.

Stu
Well PVC elbows weren't working to well either. Couldn't get equal length
pipes to end up in an equal place. Next tried 3/4" steel flex conduit. OK
it proves that you can get 4 equal length pipes to end up at the mouth of
the 4-into-1 collector. It does prove that the required bends are not
simple. However the steel flex conduit is heavy and tries to sag. Next
tried some 1- 1/4 flex aluminum conduit. It isn't heavy but it too sags
all over the place. One thought was to get the conduit in place with
support and then put a bunch of tack welds to make it solid. Yep the
conduit is weldable but it will take welds on both sides to make it rigid.
Next trick being tried is using an expoxy to coat and stiffen the flex
conduit. Also trying some permanent thread locker and some 5 minute epoxy.
Sure would be nice to have some medium that was flexible but kinda stiff
that could be treated with some easy to apply medium when the proper angles
were achieved to derive a stiff pipe that could be copied in SS. Any of
you wizards out there have any ideas that might help a sr.citizen having
trouble?