It doesn't matter how fast the arrow is going if you can't hit what you're aiming at. 3555's would be way underspined for your setup and you'll never get two to shoot anywhere close to the same place. You NEED the 5575's. The difference between 8.2 grains per inch and 7.4 grains per inch is a mere 24 grains on a 30" arrow. Something like 3-5 fps.

If you simply MUST get down to 5 grains per pound then you need to select a different brand. High Country is putting out some ultra-ultra light arrow shafts for guys who like to dry fire their bows. Take a look at them.