Help with soil.

I am going to purchase Hyponex soil. But I would like to lighten it up a bit to provide better drainage and most of all easier room for root growth. What could I add to the soil to lighten it up? Im thinking coco coir. Any opinions or advice?

Also I was thinking of adding a little bit of soil from my outdoor veggie garden in hopes of providing some of the stuff ancient forest humus provides. Smart or no?

I think perlite and coco coir would fit the bill. I use both for the same purpose.

Bringing in the outdoor soil is controversial. On this organics forum, people would probably be for it if you know you have quality stuff. Some less organic people would say it's a virgin like having unprotected sex with a prostitute. You have all this clean, virgin stuff in your clean indoor area and then you bring in god-knows-what. If you bought some forest humus in a bag, the price would be a bargain compared to the work of trying to get rid of a potential problem.

I store soil outside in containers and bring it in without problem. I have also brought in composted manures and kitchen compost without problem. I have brought in outdoor plants in containers that turned out to have white flies that were a bitch to get rid of. Those were on the plants and not in the soil though. I have never just brought in veggie garden compost. Kinda depends on your level of confidence and willingness to experiment.