These kits use Mercury Marine IGN coils (or aftermarket equivalents). PR says the coils they use have a different winding. AEM sells some as well and incorrectly calls them "LS1 dumb coils". You can buy the coils from many places.
Spool has agreed to no longer selling the kit and while it was for the F series N55, I made it work on my E series N55 and it works great on my FBO E50 tuned E90 335i.
I do really like the Spool coil bracket though and the quality of the coils and wires is really good, although I cannot compare to the PR kit, as I have not installed one.
This is still VERY wrong, I feel like a broken record here. The shell of the coil is Mercury Marine. However, PR (and hopefully Spool) are in NO WAY SHAPE OR FORM mercury marine OEM coils, other than a few base specs that lend themselves very well towards reliability in those marine applications. The Mercury Marine coil is CDI.... what that means is the resistance is around .05 ohms on the primary, 10x lower than factory BMW coils. This is because CDI coils use step-up transformers to charge with hundreds of volts input, which translates to hundreds of thousands of volts output, but they charge for an EXTREMELY short period "dwell" and fire multiple sparks in succession. This isn't like multispark at all, CDI is NOT the same as inductive coils. If Spool is using Mercury Marine coils like many say they are, then you are going to run into issues with 1) current limiting on the DME due to 0.05 ohm load drawing WAY too much current even at 1ms dwell, generally manifests by ignition shutoff when it overheats for about 30 minutes to cool, or could burn the DME. 2) Low output as CDI coils are designed for high voltage, low current, multiple successive sparks with a CDI ignition system. 3) Failed coils by overheating. 4) Poor performance of the coil... we actually tested the MM ones during development with inductive drivers for fun and they handled being overdriven surprisingly well, still outperformed BMW, but you cannot and I'll say this again CANNOT use CDI coils with the N54, N55, or any inductive ignition system or something will eventually break.
If you run other coils (msd aem etc) make sure they are INDUCTIVE not CDI as they make both versions. You will have to figure out dwell as it will be different. The AEM dumb coil might be a dumb version of the LS coil, there's nothing keeping them from using LS coil specs. My testing results of the LS truck coil are posted it's good but not great, especially for high rpm. Needs too much dwell and that pushes duty cycle up when revving to 6k or higher. Specs on PR were chosen for a reason assuming 8k rpm targets for full dwell without exceeding 40% duty cycle.
