Ignition coil packs?

[Slingwing 317]

Do upgraded ignition coil packs really make a significant difference in performance?

"Shown to deliver up to 15 HP on naturally aspirated engines, and as much as 30 HP gains on supercharged or turbocharged (and nitrous) applications, these coil packs not only gain power, but also can add fuel mileage and improve cold start characteristics & driveability, but they're also far CHEAPER than a brand new set of those weak factory Ford coil packs!"
-Troyer Performance

I'm wanting to know if it's worth the investment prior to ordering a Gryphon or is it snake oil?