With lithiums you will need a regulator for the receiver/servos, and probably for the ignition depending on what ignition it is.

You also are putting way too much capacity on the ignition, if you are using 2800 mah on the rx you will need only about half that on the ignition to have equal endurance.

If cost is significant, we sell a 2100mah nimh pack for $28 (sanyo cells) and a 1200 for the ignition for $22. $50 gets you in the air, and $30 more for 2 switches. Performance will be very close to Lithiums, the difference is thet lithiums will have a more consistent voltage since they start out higher and are regulated down. Most people will never notice it.

TF