Check this thread out:
http://www.svtperformance.com/forums/2013-shelby-gt500-413/883827-700-rwhp-easy.html
That might help you decide on what you want to go with
http://www.svtperformance.com/forums/2013-shelby-gt500-413/883827-700-rwhp-easy.html
That might help you decide on what you want to go with