The 1.8L coils have a lower resistance than the stock P5 coils (according to the tech manual). This equals more spark supposedly. Locating the coils away from heat is a fantastic idea for longevity. Mazda's bright idea to put them on top of the VC was surely just a crappy attempt to save money (regardless of voltage drop that a spark plug wire might impose, it still sucks). Nology makes a kit like this too, but my experience with those wasnt good. The jackets crack very fast and there was no noticeable gain (especially for the cost). The 1.8L conversion is the way to go, unless you have a standalone of course....