S2000 RobMod Race Exhaust
By Rob Robinette
I needed a very lightweight free flowing exhaust for track only
use. I had a spare stock exhaust so I cut it just before the "donkey dick" that
sticks out sideways. I then welded on a Morroso racing muffler with 2 1/2 inch
inlet and outlet. The muffler flows about 70% of the exhaust straight through
and 30% goes into a spiral around the primary flow. The muffler will just slip
over the stock exhaust with a perfect fit which makes it easier to join and weld.
The stock exhaust was cut off just before the "donkey dick." I used the stock
center exhaust hanger perch to hang
the pipe.
I clamped on a 2 1/2 inch turn down on the exit flange of the
muffler and attached wire from one of the clamp bolts running up to the mid
exhaust hanger.
Running this exhaust with a stock header, resonated test pipe in place of
the cat and the turn-down pointed away from the sound meter I registered 98dbi
with a 103dbi limit at an SCCA event. I also put the car on the dyno at RP
Performance and Bret, the owner of RP, was surprised how quiet the car was but
keep in mind he's used to Spec Miatas. The resonated test pipe makes a pretty
big difference with this exhaust, with a test pipe it is quite a bit louder.
After two years of use this exhaust system is still going
strong.
The exhaust is loud but it's much better than a truly open
exhaust.
Rob Robinette
|