Difficulty: 2/5
Time to install: 20 mins for immediate install and test, plus whatever time left you want to spend removing remaining OEM parts or wire looms
Tools Required:
Socket and Ratchet set to install new spark plugs,
Drill and/or screwdriver to mount the coil driver.
Like many boutique Miata parts sometimes vendors come and go. So priority 1, document a few things for future maintenance:
Ignitor
Bosch 0227100211 or 4D0 905 351 - I've used this ignitor and confirm it works.
Or the Meyle equivalent brand
Coil Packs/Coil on Plugs
Denso 129700-5150
Denso 129700-5140
Coil on Plugs for a 2008-2009 or 2012-2019 Suzuki GSXR 600
Spark Plugs
The most important part here is that the plug connector can screw off.
Bosch Super Plus 7956 - This is 1 step colder for a 1991 Miata - I've used these plus and confirm it works.
Bosch 9652
Should the igniters die in the future, it's a Denso and printed on the side is: 129700-5230 JO523 03P0512028. Not sure if that's the whole part number, or some of it and other numbers are a manufacturing lot number. I guess I'll figure that out someday should they need to be replaced.
The kit uses one of 3 Denso "Iridium Power" spark plugs, depending on your application:
Naturally Aspirated: IK16
Forced Induction < 16psi: IK22. Note, I bought this setup. Here's other info from the box:
0.4mm gap
IK22#4 / 5310#4 / I03
Forced Induction > 16psi: IK24
Instructions attached at bottom (no PDF available on vendor site).