gmookher said:
S4 is a 2005.5
ever hear of these guys?
http://www.stratmosphere.com/s4_b6.htm
yeah been thinking about sway bars, but soft slides so evenly and gives very gradually.
Funny on the .5, I drove a Mugelo Blue one last summer which got me thinking about them. FYI - Don't get swept up in chip dreams, they really don't do much for the V8.
Stratmosphere looks a little amateur and just a supplier, not a builder, check this out, pure serious Audi aftermarket, they even got Audi to warranty their stuff when installed by dealer:
http://www.stasisengineering.com/
I have their center differential replacement, it's basically a slightly better version of the one in the latest RS4.
This is the best installer in the Seattle area, they know everything you could want to ask about your S4:
http://achtuning.com/
If you can part with $10k, you can turn your car into a 440 hp beast with the US built Supercharger by VF Engineering in Cali.