Well first to start off... I traded my Legend Lime GT Convertible in for a White GT Coupe. Both cars are autos.

I went to the track today & the Coupe is running /way/ slower than the Convertible did when it was stock. I hit 14.0 numerous times in the Stock Vert and the best I could muster this time was a 14.45 and got as bad as a 15.

There are a few differences I can think of between the two cars, the Vert had 18" all season BFGoodrich tires, this one has 17" P-zeros. Vert had Shaker 500 which I think is lighter... Coupe has Shaker 1000... the Vert is heavier to begin with though.

I just want to make sure there is nothing wrong with the new car, or any common things that go wrong with these cars that hurt performance. It might just be me getting used to the car though...

Any input appreciated.

 

Slap that CAI/Tuner onto the new GT and your worries will be gone. The adaptive learning may have had something to do with it. Also the weather probably played a major factor.

 

Yeah I hope so... I have some mods on the way too New CAI/Tuner, Kooks LT Headers & X-Pipe, Pypes Mid Muffler system.

 

problem solved....^^^^ if the car is not throwing codes and drives fine I doubt you have anything to worry about. Not all stangs come from the factory created equally.....I bet not one is the same though might be close......quality vs. the idiot that could care less making the car.... JMO

 

Did you happen to get 3.31 rear end gears in your new coupe? 3.31s paired with the pirelli 17's (which are taller than the bfgs and further reduce overall effective gear ratio) would make it significantly slower due to you not having enough torque multiplication to the ground.

 

what he said^^^! and if you have the same gears then it's all in the factory tune...

 

Not sure. I ran 13.80's @ 103 all day bone stock with 3:31 gears and the 17" P-Zero tires. After a slight tune and a drop in K&N (turbo kit coming so no CAI for me) i dropped down to a 13.52 @ 105

Edit: I have a manual though.

 

Well will run it again after I get some mods... then see what happens

 

I think you have the tire sizes backwards

235/55/17 pirelli = 27.2 inches
Vs.
235/50/18 BFG = 27.3 inches

The 18's are a .1 larger than those stock 17's so 17's would in theory accelerate quicker. That is only theory as the BFG's are way stickier and hook better out of the hole

 

Thanks for the correction. For some reason, i was thinking the 18's were 45 profile.