We have found that the Gas platform of the OEM gas system is unsuitable for performance upgrades.
I am lead to believe ford have stopped production of the gas cars ATM due to blowing head gaskets with the new gas system they are trying to use for the EURO4 standards. So i can only speak for the old gas system.
If you want a performance car look at petrol engines .. far less worries and engine problems.
IF you are only wanting a gas car then give the guys call at
http://www.alpgw.com.au/ for more option .. they are also a site sponsor