Heavy Forwarder System Requirements

Hi All, We are trying to size a AMI Linux VM Heavy Forwarder for a new installation of 6.2.6 and have found the Splunk recommended system requirements of 2x six-core, 2+ GHz CPU, 12 GB RAM at the following link: http://docs.splunk.com/Documentation/Splunk/6.0/Installation/Systemrequirements#Recommended_hardware but there is no specific mention of the requirements for a Heavy Forwarder anywhere that we can find in any Splunk documentation. We have found high level reference to the fact a forwarder can be of a lower spec that the above as it will not be doing as much indexing as an indexer but no quantification as to what that less may be... Any guidance or advice that anyone can provide would be much appreciated. Thanks