I know if the spine is too weak there will defenant flight problems. But if the arrow spine is too stiff will the same problems arise? Will it still effect flight as badly if you have a good FOC?

Check out this link:
Ragsdale on Overspined Arrows

This is a link to Bob Ragsdales FAQ section of his website and it contains a lot of interesting and valuable info.

Thx Mouse,

Glad to have the experience validated by Ragsdale. He does a kickin bootie column. Fact is in our quest for speed, flatter trajectories, and greater distances we go to the lighter arrows. This commonly results in our pushing the edge so much we underspine our arrows. In point of fact, there is a theoretical point at which you can overspine. Don't think a bow would shoot a telephone pole. In fact most of us never waiver on that side of it tho.

I would agree, you can have too much spine. But it's not going to be as detrimental as too little spine. It's probably more critical with aluminum than carbon arrows. I got some PSE Extreme 300s finished and shot today with them. These are over-spined for my bow's draw weight, given a 28" arrow. They fly and group great! I think the spine charts generally don't consider the difference in efficiency achieved by today's bows. A bow shooting 315 fps at 60# is definitely going to stress an arrow more than a 60#er shooting at 285. I decided to try the 300s due to this. The initial finding is, these shoot better than my Redline 410s or 460s, which are OK for my setup (by the chart).

Phil.
"Could you guys be quiet, my dad's trying to shoot."