Hi Paul,

Why not use the original exhaust manifold form Mazda?
Besides the weight, are there any other disadvantages?

Would a Mazda manifold covered by a heat shield connected to a Spintech
muffler do the job?
I understand there is a 10 to 15 pounds weight penalty and I am probably
oversimplifying but my understanding so far
is nothing worked and there are critical safety issues; also it seems to me
it is getting expensive for a muffler, specially if
it has to be redesigned and rebuilt every 30 hours.

JP


Yes that works fine. Perry has been running one for years.
No real disadvantages but down on power somewhat. How far
down I don't know.

Most street car mufflers use thin mild steel .025" thick or thinner.
304 SS is a step up. 321 SS is another step up.
0.035" thick Inconel works fine.

0.035" thick 321 SS perhaps is not quite adequate depending
on how far the muffler is from the exhaust.

0.049" thick (40% heavier than .035") 321 SS ought to be fine in most cases.

Thicker works fine. The question is how thick. Some have used
3/16" thick 304 SS hand rail and that hardly discolors.

The idea is to reduce the thickness of the material as you
get further and further away from the exhaust ports.

If it is tangential muffler you can beef up just the local
area where the blast strikes the wall.

These are all educated guesses based on ten years of 12A/13B muffler reports
and experiences of others. There are a lot of variables.

The RX8 engine is too new to have extensive experience/history but it is
somewhat easier on the exhaust system as it is 200 F cooler
and has less kinetic energy.