You know. Thats a good question. The factory air box isn't going to be a great heat shield, but its better than nothing, on the other hand the first one has a longer pipe, and a potential for greater, colder flow.

However, those two pictures look differenent. In the top pic the A/C condenser is against the firewall, but not in the bottom pic. The top pic looks like it's mean for a Ram, and the bottom pic looks like it's meant for a dakota. But I could be wrong.