Tranny Loss
 

I own a 03 GT and recently read where 18% of the car's HP is lost through the tranny. Can someone tell me how to lower this % with some modifications?? :(

The 18% loss is just an estimate. No actually knows an exact number. It ranges from 15-18% for a manual tranny, and 18-22% on an auto (these are numbers that I have seen in the past). There isn't really anything that you can do to reduce the loss from the drivetrain. The only thing you can do is swap in a manual tranny if you have an automatic.

you can help lower it buy using a fluid like royal purple. it is the friction that robs the power in the drivetrain.

The royal purple fluid is the exact same as the type f fluid with a purple color. Be careful that this fluid is compatable with your thrust bearings. An aluminum driveshaft might help a little. the 18% is through the drivetrain not just the tranny (I think) The lighter drive shaft will be less rotational weight and you might feel a difference. I would upgrade the rear end before messing with the tranny. Maybe some high performance bearings and lighter oil? While your at it, through some new gears in there, they won't improve your effeciency but it will rev faster.