Bosch CDI units can be repaired - I have done lots of them. That takes the price differential out of the equation. Plus I don't like splicing wires and cutting into the harness when you can keep your car stock. It creates more points for failure down the road due to corrosion and such. I'd always stay with the Bosch unit if I had a choice.

I agree with JW that the adjustable rev limiter is a nice feature of the MSD and for purpose-built cars MSD seems to be a popular choice when building an ignition system from scratch. The performance improvements are a good marketing campaign with little physics to back up the claims.

BTW, when you read Wayne’s 101 book you’d recognize that nearly half of the projects start with the exact same preamble: “One of the most popular upgrades is……” I guess it’s just his way of starting a sentence. It’s like my old boss who started a sentence with: Don’t we all agree that……” every time he came up with some BS that he knew was not going to fly :rolleyes:

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'74 911 Targa 3.6 - '01 911 C4 -



3.6 w/carbs or MFI and Bosch CDI


nice

What generally fails? Capacitors due to age?

Just curious.

The capacitor is one comon failure but I see all kinds of failures (SCR, trigger stage, circuit board, overvoltage, snubber, DC/DC converter, etc.)