Reducing weight of Big Agnes tent

I consider the minimum weight of a tent to be the tent and poles. Changing stakes or guy out lines would be done before the trip based on expected conditions: sand, snow, ice, solid bedrock, soil; then number needed, etc. That is a reaction to an environmental requirements, and not really lightening a tent. You take the lightest stakes which will work in the expected surface.
You are right, those items can really affect the total packed weight.

Ways to reduce BA SL1 weight:

1. Swap out 11 stakes for titanium ones (0.26 x 11) = 2.9oz saving.

2. Swap out aluminum pole for carbon fiber – approx. 4-5 oz. saving.

Total comes to about half a pound.

For me, I would swap out the stakes because the V-stakes that come with the tent are hard to use. Titanium shepherd hooks are just so much easier and lighter — and not all that expensive. You might, however, want to keep one V-stake to use as "drill bit". If the ground is really hard, you can use it to make the holes, then insert the titanium ones.

As for carbon fiber, that is a much more expensive option.

If your tent is 2006 or later, the guylines are already pretty darn light. You can find even lighter ones, but the weight savings will be pretty minimal.