it depends on the route you want to go, if you want to spend over $1k dollars on springs and shocks, go with coilovers. Personally, I'm going to buy some eibach springs and bilstein shocks (though I have KYB's right now), and with that package I'll be lowered, and handling better. Exhaust and intake is one of those "pick one" issues, personally I'm going after HKS exhaust and a K&N intake.
Tranny jumping could be the tranny mount or the tranny is messed up, right turn squeak could be anything from brakes, suspension, to steering.
The cover for the back isn't cheap for a new one, I'm seeing $280 from
http://www.trademotion.com/partlocator/ind...m?siteid=213747