I personally found this out the hard way. While taking my wife's car, a 2004 Pontiac Grand Am, to get the oil changed, I noticed that the vehicle had a "bouncy" feel to it. The handling was very unpredictable and I could feel every imperfection in the road.
In looking at damper options, we had our local mechanic install KYB struts in the front and rear of the vehicle. What a difference this made in the way the vehicle rides! One quick tip: always try and change out both the mounts and boots when replacing suspension components. Nothing like new products being held to your car by worn-out mounts!
For those looking to increase their vehicle's performance, consider the options available from H&R. They offer some of the best suspension components for improving handling and performance for many vehicles, including the 09 VW Jetta TDI. In addition to struts, take your suspension upgrade to another level with the H&R Coil-Over Premium Performance Kit. And to gain a better understanding on improving your vehicle's performance, read "Minimizing & Controlling Bounce."
After you've purchased suspension components and had them installed, don't forget to fill out our Suspension Component Survey. This will provide others with reviews and help them select the proper suspension products for their vehicle.