I am in a similar place right now. I love the new Mustang GT. But I also love the 13/14 GT500.
If I got a 15 GT I would want to add a blower to it and then there goes my warranty.
If I want to take my blown 05 any further it will need a built motor and supporting mods and with my Saleen blower 600rwhp is about the max its gonna get me.
The GT500 will get me 11 second timeslips bone stock and have a warranty. But they cost so much It would take me a while to save up cash to get the payment to a comfortable level.
For now I will continue to race my 05 GT and save up money for the future when I will decide what route to take. All three options will get me around 550-600rwhp but only one will get me 600rwhp with a full warranty. But I will have to pay out the butt for it.
And the GT500 would possibly be the first Mustang I would not modify. I think its close to perfect from the factory.
2005 Ford Mustang GT Torch Red Manual
Saleen Super Shaker 3.4 pulley/Brenspeed Tune
Kooks Longtubes Catted H/FRPP Stingers
Full BMR And Steeda Suspension
SOLD!! I have no Mustang at this time!