It won't void the warranty; but if the tune is proven to be the cause of damage to the engine, then, yes, the dealer does have the right to deny warranty work.

Some dealerships are shady and will attempt to submit voids for stupid crap; I have heard of cases where a service center attempted to submit a void because someone replaced the worn Pirelli tires with non-Pirellis.
Get to know your dealership service center and find out what their stance is on mods. If they are anti-mod and make overtures of attempting to void your warranty, do not do business with that service center. Then tell the dealership GM about how you disapprove of their anti-mod stance. Continue on to another Ford dealership service center and feel them out.
Doing this ill send a clear message to the service centers that are anti-mods: The mere mention of "void" means loss of business to a more customer oriented service center.

If you are going to get a tune and intake (Boss 302 intake for example), buy a tune from American Muscle and BAMA, they have a specific warranty for the #8 cylinder and AM/BAMA have stood behind their warranty and tunes 100%, even stepping in where the dealership dropped the ball.

As for the 6R80 automatic transmission, it has survived serious abuse. Professional modders with FI 'Stangs have run 10s on stock 6R80 gearboxes without any issue at all.

 

Just like what he said: you can adjust the steering feel, from sport setting to a mild DD setting.

Another key difference I can remember is the MT82 manual transmission got some minor revisions to help address complaints of rough shifting. But since you are looking at an automatic (6R80 gearbox), this is not too relevant.

If you don't mind a 2013, the '13 GT did away with the piston squirters and attains just a little more top end BHP, the Coyote now making 420 BHP over the 412 BHP of the '11 and '12 GT.

 

Ok I will keep this in mind

 

I can vouch for the 6R80 transmission. the 2011 I traded had that tranny, and I put that car through serious hell. Like I noted in my thread about my new 2013, I had the exhaust mods finished Friday afternoon, then traded the car Saturday afternoon. But that 24 hour period in between... I went on a rampage with it, especially between 7 and 11pm friday night. I was tearing it up all over the DC metro area. =O)

That is why I never knock the automatics, they can handle some serious abuse.

 

Keep the GN.. They are beautiful cars. Id just sell your stang and save up for a while and then get a new 11-12 Mustang.

But what ever you do dont sell the GN... Unless you want to sell it to me... haha.. just checking.

 

Hmmm I might just keep what i got i like having a vert anyway.....I'm going to give it some more thought.......sounds like you guys would not make that trade based on what i'm hearing.

 

Hell No... I would get rid of the 98 Stang, but no the GN. NO F***IN WAY. I love me some fords, had 25 Mustangs, but If I had a GN or GNX, you'd have to kill me before I traded or sold it.