SlideWRX

If the back end is light at high speed, he needs downforce/less liftat the rear, or less downforce at the front; doesn't matter that the car is a 'brick'. The Mustangdoes pretty well in the Koni street challenge, beatingup BMW's & Porsche's. It's a very effective track car.

suoperdave84

S197steve

The shape of the car has alot to do with it as well. The more severe the downward shape of the rear of the car, the worse the rear end lift will be.

For example, the Audi TT was originally built without a spoiler. But after several very highspeed incidents where they lost rear traction, a recall was made and they were fitted with a spoiler.

The Mustang already has a 'notchy' backend which should break up the air flow just fine... you won't lose anything by adding a rear spoiler, but then again the gains will most likely be so minimal that you won't notice anything.

As mentioned earlier, a properly sprung car will provide MUCH better results that a rear spoiler...

SlideWRX

I don't see how, if the issue is just at high speed. spring rates don't change with speed. If it's still an issue at lower speed, then yeah the basic balance is off.