Gears, gears, gears and gears. The 4.6 DOHC makes no torque under the curve and going to a shorter gear will help you get that motor up in its powerband so much quicker. Plus, it will feel like you gained 50hp at the seat of your pants. I went with 4.10's, there are a ton of write up's on this on the SVTPerformance site. I don't think you will be disappointed.
Don't Fear the Gear!