Quick thanks to Kim and the guys at QS Tuning...

[s4dave]

...who sorted me with H&R anti-roll bars, front and rear, at short notice last week.

Even though I'm still stock height (pending resolution of a "driveway undulation issue" ) they've made a significant difference - body roll is greatly reduced, car feels better balanced on turn-in and exit, and that "floaty" front-end feel of stock suspension is completely gone.

Even though they overran their estimate a little the labour still came to half what <cough> Audi dealership charged me to swap over a TBB the day before!

Highly recommended and my S4 will certainly be going back there,
Dave

[Dippy]

Dave,

The TBB is a weak point in your car and should be regularly inspected. It really is such a simple job to do, unless you are really a 'hands-off' person I would advise that you learn how to (IIRC DavidT is the expert).

[s4dave]

Dippy... yeah, I know, will definitely DIY it next time but I'm just a little paranoid about doing anything that might give them the excuse to void the warranty on the Turbos...

[DavidT]

I'm no expert (SiTa is though) but they are easy to change.

I'm for getting a samco one or even the APR bi-pipe as you have Dippy, the last TBB failure on my car was the suspected cause of turbo failure and a £3.3k warranty claim.