Absolutely nothing!
Let me first say something about the strength of a Subaru. My previous car, a 1996 Impreza LX was slammed into, while at a stop, by a tractor-trailer going 25 miles per hour. All the force of this crash was transmitted through the frame of my car, and was unleashed on the two cars in front of me. Needless to say, no one in my car was hurt, but the two people in front of me were, and both of their cars, a Dodge Neon, and Toyota pickup were totaled. My son owns this Impreza now, and drives it all through the mountains of Virginia. Just try to part him from his car.
My new car, an Impreza RS is a fantastic car. It is not often that something can totally erase the effects of a bad day at work, like this car. It makes it a pleasure to scorch those ponderous Yukons and Suburbans. On more than one occasion, I have had "goobers" in VW GTI's and BMW 3 Series pull up beside me, only to find that they did not have time to read the nameplate, getting progressively smaller, on my trunk!
Have replaced the factory 13mm rear sway bar with a 20mm one. It makes a great difference. You can take curves 20% faster.
The factory sound system is a little suspect, but if you are like me, the windows and sunroof are always open. That is certainly the least of my worries.
Once you drive this car, you will have to have it!
Good to hear about the safety in a crash - hopefully I won't have one in my Impreza! You should come over to the UK sometime and try out the 276bhp versions - try logging onto bbs.scoobynet.co.uk for an excellent Impreza forum.
When you say "The factory sound system is a little suspect" what do you mean by this statement?