Wihout wishing to knock Splitfires all you are really saying is "if your coils are stuffed putting new ones in will make your car run better".
What would be more useful to know is stories of failures. We know that the Nissan coils are good for around 15 years (and I have seen two examples recently of people who have forked out for new stockers on the strength of this i guess) so it would be good to know how long before Splitfires, Yellowjackets, DSRs and other aftermarket coils start failing.