Replace Ford 5.4L Coil-Over-Plug's with standard coils?
I've got a '99 Ford F150 with a 5.4L V8 that runs Coil-Over-Plug assemblies. My pickup has 180,000 miles on it, so I'm going to take the initiative and assume one or more of them will go out in the not-so-distant future. However, I don't want to have to spend $45/COP when I change them (or replace them more than once), so I'd like to replace them with standard coils. Even if I get 8 "standard" coils and mount them on the firewall it'll still be cheaper than getting new COP's. Also, with the right (hotter) coils will likely perform better than stock.
My '98 Ranger (that was wrecked and totaled) had a 2.5L 4-cylinder with 8 spark plugs and 2 coils, each having 4 plugs attached. This is where I'll start my investigation; mounting 2 coils would be easier than 8.
I'll likely need to find coils with the same primary impedance so it won't throw the ECU off. I wouldn't mind having coils that put out more spark power (would prefer it, actually). Does anyone know what the primary impedance is on the COP's?
Electrically 8 coils would likely be the simplest, since the engine already has 8 individual coils. Also I would surmise that 8 individual coils would last virtually forever. However, mechanically it may not be quite that easy. I could possibly mount 2 banks of 4 coils somewhere on the firewall.
What all should I look out for when doing such a conversion?