I'm afraid your just not being realistic about your proposed mods. Upgraded coils will do NOTHING for this application. Cams will be mega bucks and bumping up compression will be big money too and require more than several days down time unless you buy another engine to mod and swap in a day when done. The labor costs alone for your proposed mods will be $$$.

Your best bet, as has been said over and over is gearing. You will keep OEM reliability, gain "power" and save a ton of cash that can be used to buy gas.

Myself, I am working on doing serious power mods for my V10 but I know I will spend a mint, lose MPG....and LOVE it.