Personally, im not a big fan of the L96. It's very big, and bulky. If your trying to sneak around, you want to be as low profile as possible, but a 5 foot gun doesnt help much.
If its you taste, cool. I would say check out:
www.x-fire.org (click on english tab) and you'll see that upgrades PDI has. From what i see there, not very much. But im not really experienced at all yet, especially with the L96.