I found this video posted by the guys over at Turn In Concepts:
Suspension travel: GOOD
Cheap coilovers: BAD
A stock Subaru has about 5.75″ of front suspension travel, and nearly 8″ in the rear (except for multi-link cars, which only have about 4.5″).
The reason this travel is important is to keep the tire in consistent contact with the road. The better the contact with the road, the more grip. Reduce travel, and the suspension can bottom out, overloading the tire and causing a reduction in grip. On the other side, with less travel you are also more likely to pick a wheel up off the ground. And that means no grip.