Don't know if this has already been posted or not...Yesterday I picked up a copy of MM&FF on page 126 they have an 03' cobra making an extra 25HP with ONLY a K&N kit?!? I thought this was very interesting...
My question would be could this same install be done on a 99+ Mustang GT?
Yes, it's true that adding a CAI kit to a supercharged vehicle (such as an '03/04 snake) will yield excellent gains. However, you'll be hard pressed to see those types of gains on a naturally aspirated engine. So, you probably won't see +25HP on a '99GT...
I felt it on mine... gives 1 pound of additional boost... enough to hear a bit more whine from the hood... check out my video and you can here the aggressive fly by... I never knew you could hear it outside the vehicle so well
That test was done at the shop that has done all my work. The tuner, Lidio, started selling this kit at his shop for all 03+ Cobra's. With the s/c he was seeing 1 additional lb of boost.
On an n/a car such as yours, a CAI kit will probably get you around 5RWHP at best....JMHO.
Two reasons.....first, the 03-04 is a supercharged engine, and the boost pressure magnifies any changes in airflow. Second....the intake on 03-04 Cobras is quite restricted by the airbox to fender snorkle, and to some extent on the backside with the exhaust. Getting rid of the intake restriction makes a big difference.
When the car was first introduced on of the Ford engineers was quoted as saying that it's "breathing through a straw". It is, and that's why intake changes can give some much seat of the pants power differences.