My car (1991 Miata) has been acting up when cool and humid, popped the hood one night and the solution presented itself. One of the coils is shooting sparks out a crack that when the engine is warm seals itself up. Any good upgrades for the coils (possibly turbocharging down the road), running MS now, and am in general upgrading as stuff breaks.
Someone on here runs an MSD box in their Miata with good results. Lots of turbo guys swap to Toyota coil on plugs. More info here:
http://www.miataturbo.net/showthread.php?t=12704 and here: http://www.miataturbo.net/showthread.php?t=18937
PS. Don't post on that forum. They aren't kind to new folks.
If your MS can run sequential ignition, put in the LS3 coils.
The Toyota COPs don't actually test well on the bench, they're a cool idea but not necessarily an upgrade.
This is what we're running on our own turbo Miata:
http://www.diyautotune.com/catalog/ign1a-race-coil-p-394.html
LSx coils aren't bad for a low buck upgrade. Or take the coil and module off a turbo DSM, it's basically a hotter version of the Mitsubishi-built Miata ignition. Our experience with Toyota COPs matches Keith's - nice packaging, but not really all that hotter.
Good to know about the testing of the COPs. I put mine in when my stock coil was damaged since it was cheaper than a replacement coil, but I now have 2 spare coils from an extra engine. Maybe I'll reinstall the stock stuff and see how they work.
I mounted a dodge neon coil to my valve cover, it was essentially plug and play and works well.
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