I bought 6 or 7- 4" radius 2-1/2" diam. Mandrel bent steel pipe
J-bends from Hooker and fabricated my own exhaust piping. It was
run so that it is no lower than needed, and in fact, the only place where
it is lower than the rest of the car is under the trans mount, by a 1/4".
I used a modified 280Z front differential crossmember (see pics below)
so that two 2-1/2" pipes would be tucked up well at the differential. (Note:
On the picture below where the unpainted crossmember is on the bench, I
had not added a thicker piece of steel into the new opening. It is
present on the installed pictures.)
I also cut off the ears on the differential case that
extend out beyond the rear cover at the lower corners to gain clearance
there. The entire system is no lower than the rest of the car except
for that one short area below the transmission crossmember.
(Click on above picture for larger version)
Cross-over Pipe: I'm used a 2-1/2" Dr.
Gas X-pipe, just behind the transmission. This is supposedly
better than a regular H-pipe arrangement. I bought just the Junction,
not the kit, since I have a bunch of mandrel bends around ;). There
are bolting flanges just forward of the X-pipe.
Mufflers: Dynomax Super Turbo Hemi Mufflers: 4
1/4 in. x 9 3/4 in. oval, 2-1/2" center inlet - 2-1/2" offset outlet (P/N
17748).
These are very efficient mufflers. They are quiet, have relatively
low back pressure, and a deep throaty sound. They do well in many
of the muffler comparison tests. The problem is that they are long.
These mufflers have a 20" long case. Fitting two of them side by
side in the stock Z muffler location required spare tire well surgery (see
below) and some tricks turning into the muffler without hitting the rear
control arm. For the left muffler, I cut the entire nipple
off the inlet of the muffler and use a 4" radius ~90 degree bend into the
muffler. For the right muffler, I again cut the nipple off the muffler,
and used a very tight bend in front of the muffler. I found that
The
Chassis Shop makes something called a "Donut" that is basically
a donut of muffler tubing (see collage picture of uncoated exhaust below).
The 2-1/2" diameter pipe Donut is only 7" in outside diameter. If
you cut a ~90 degree section out of it, you get a tight enough bend so
that there is 1" of clearance between the control arm and the pipe.
As noted above, to get two of these side by side, I had to remove a several
(~5) inches off the diameter of the spare tire well. But this
was also to make enough room for the biggest 17" tires capable of fitting
in the stock fender (using 2-1/2" coilover springs). The inboard
edge of the sidewall is a mere inch from the vertical part of the inner
wheel house, so the mufflers must be moved over to pass the tire.
From the left wheel well, with a jig to mock the outside extent of the
wheel and tire, this looks like (that 82 disc is now replaced with a Wilwood
one from Arizona Z car, by the way):
..and from the rear (I need to fill in the stock opening a bit):
Here are some pictures of the completed system. Since the pictures
below were taken, I've cut the pipes before the mufflers, just before the
last bend into the muffler, and installed more 3-bolt flanges. This
was so that I could send the entire system to FL to be Stainless Steel
Ceramic coated by Baxter Custom Engineering,
except for the mufflers and the short pipe before them. Just below
are pictures of the system before being coated.
I had the headers, and all piping and flanges up until just a foot before
the mufflers Ceramic/Stainless steel coated, to keep it from rusting, and
more importantly, to keep heat out of the engine compartment and out of
the interior of the car. (Pictures below.)
Looks a bit better, no? It looks much nicer than the pictures show.
Of course, they spent 3 hours of labor on cleaning up my welds, etc.
They did a heck of a nice job. It looks almost too good to put under
a car!
Since the above picture, I painted the pipe from the flange to the mufflers
with silver Miracle paint from Hirsch Automotive. It might end up
burning off, so I'll keep an eye on it. The mufflers were too large
to fit in the kitchen oven, as I was going to use Tech-line's aluminum
ceramic coating on those.
