pretty well compared to most cars of the MX5s era, according to the
documents I've read, and especially when the car is only 120hp. I also like
the sound of the stock exhaust - and the fact that I am helping the
environment*... A cat can be removed pretty cheaply though, and can be
replaced with a straight pipe, or a small resonator which should help keep
the exhaust note. I wouldn't recommend hollowing out the cat, as some
people do - I've seen this result in a very tinny/rattly exhaust sound. I
got my last car's (MX6) cat replaced with a resonator for about $40 a couple
of years ago.
* however if you believe the latest reports, (recent New Scientist mag)
catalytic converters are doing more damage than good, as when destroyed, and
also while they are in use, they leech heavy metals like platinum into the
earth and waterways...and you thought this was just an MX5 list
