i have a 98 audi a6 2.8 quattro and was wondering if i can use h&r sport springs with stock parts? and will i be able to add the h&r race springs with stock or need to upgrade?

 

You would probably be able to get away with the sport springs for awhile, but their lower height will likely accelerate the wear on them. The race springs are a big drop and will almost certainly kill your struts in short order. Ideally you'd upgrade your struts along with springs, so you can use struts that are designed with the lower height in mind. For a quick budget upgrade, until I can get coilovers, I put S4 springs on my A4's OEM struts, and they work great, lower the car about an inch (not much, but it helps), and the driving is much more fun - it corners better, handles better, turns in more quickly, and rides firmer. Highly recommended for a quick, easy, low-cost upgrade.