The best bang for the buck by far is Haltech. You can use the Haltech E8 for an 8 cylinder which is what is going into my 190E 16v as we speak. The electromotive only allows you to use their ignition coil packs, while Motec and Haltech can use any ignition system. Motec was just too expensive for my tastes and included many features that only Formula 1 cars need. Check it out, by far the best, and not a build it yourself like Megasquirt (although it comes out to a similar price in the end).

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1985 190E 2.3-16 Euro