I have a 2005 gt that im trying to make some upgrades too. It current has the shelby body kit on it and only mechanical upgrade is a cold air intake. I'm looking for some ideas on how to make it faster and sound great

 

Tune from American Muscle/Bama or Brenspeed should be your first move IMO

 

agreed, get a tune!

 

Intake - Tuner/Tune - Exhaust

Should always be the first things on a Mustang

 

Then gears

 

I don't know why i forgot this, but it has a diablo sport tuner in it along with the intake

 

What kind of tune? A custom written ones are still miles better than canned tunes

 

random question: do tuners and CAI's void the factory warrenty?

 

That all depends on the dealership really. I have a good one locally and no problems with all my mods.

 

My dealership hasn't even asked about upgrades when I've had to take it in for minor repairs. I don't see why a tune would void a warranty.

As for the OP, get a custom tune. If you have a custom tune, next stop is full exhaust. And if you're not planning on going forced induction anytime soon, you're next performance upgrade is steeper gearing.