Mark. The megasquirt is a complete standalone.

http://www.megasquirt.info/ms2/index.htm

Info is there

In order to have it be a full standalone you need to order the Megasquirt II which does fuel and spark. It dosent have a lot of snazzy extras, but neither does SDS and SDS is 1650.

The only 2 EMS's I would use are Megasquirt for the low end, and AEM for the high end.