Project S4: Powerflex & Whiteline & Tarox Rears Report

Project S4 has been at the health spa that is its tuning garage of choice having a chillax for the last two weeks – so big thanks to Dave Green at Henstead Motorsport (, for his usual fabulous workmanship fettling the S4 into prime, Olympic condition.

Dave has been busy fixing a couple of issues with the now 13-year-old (but still only 65,000 mile) S4; namely a front nearside suspension arm ball joint and fading rear offside anti-roll bar bush – getting her match fit for some forthcoming track days with RMA ( Job done – perfectly, as ever!

Naturally, while we were fixing Project S4 up, like the eternal modifier I am (blame rallying and my auto mag career starting at Revs Magazine!), I decided to use the opportunity to fit a few more performance parts from brands I swear by to get the old bus stopping and handling faster and harder.

First up, to compliment the bionic and brilliant big brake front kit, we have fitted a set of grooved, solid rear, heat-treated, hand-finished 256 x 22 mm discs (£202 inc VAT), from Tarox (

Then it was an upgraded, thicker (18mm), better rear anti-roll bar (or swaybar as the Aussies call them) from Whiteline (, along with a set of camber and caster enhancing bushes/drop links. “Activate more grip” is one of their sales mantras, as is “more bang for your buck” and we reckon both are true…

Last, and by no means least, we have fitted a full polyurethane suspension bush kit from Powerflex ( – designed to really freshen up the 13-year-old S4 – replacing the tired, sub-standard rubber units with stiffer, lower inertia polybushes which will last longer, work the Bilstein suspension harder and keep the tyres in contact with the tarmac. It’s quite a big job, but well, well worth it on any car, let alone an old bus like Project S4.

So, did it work?

The idea of these suspension upgrades was to liven and sharpen up the S4 and knock out some of the inertia and body roll. And bugger me if it hasn’t worked a treat! It’s almost as if I know what I’m doing after 20 years of modifying cars!

The impact of the Powerflex bushes on Project S4 is just unbelievable. The Quattro Audi now feels tighter than a Tourniquet. Gone is the getting soggy and old feeling. Hello fresh, lively, accurate, youthful feeling. The difference is simply staggering: It’s honestly like getting into a new car. Steering feeling is 100% better than before, with considerably more feedback too. Turn-in is so, so much sharper, quicker and is now deadly precise. Grip levels are noticeably higher, thanks to the Powerflex bushes working in conjunction with the Bilstein suspension to force the Dunlop tyres to make greater contact with the road. And the S4 is now capable of hawk-like changes of direction at speed, whilst feeling even more composed than usual under heavy cornering and braking too. It’s an incredible difference. Also… there’s no addition noise, which was a problem with old compound polyurethane suspension bush upgrades.

Fit a set to your car today… you will not believe the effect they have. Simple, affordable, brilliant. Thanks Powerflex: Hidden suspension tuning magic.

The Whiteline rear swaybar, camber and caster kit and links are as much of a success story too. They too have really served to lower inertia levels and increase grip and traction – by virtually eliminating body roll at the back end.

The S4 is noticeably more stable at the tail – flatter, more accurate and with a lot less movement and a far greater feeling under normal and heavy lateral cornering forces, on entry, mid-bend and on exit. It inspires confidence to push on and makes the most of the Quattro’s already excellent rear grip – again working in harmony with the Bilsteins and new Powerflex bushes to maximise the grip levels achieved by the ace Dunlop rubber. What a magic combination. The S4 is also more controlled and composed in its four wheeel drift oversteer stance, which is fabulous. We should see a reduction in tyre wear too, if I don’t do too much of that sliding stuff… although that will prove difficult, now it feels so superb doing it!

I never thought the S4 did much of its braking using the rears, but I was wrong. The addition of the new Tarox solid rear discs has made a noticeably, marked improvement in braking ability and, crucially, feeling – further adding driver confidence, enhancing the sterling work already achieved by the Tarox track day big brake front conversion and braided line kit. The relatively heavy S4 stops sharp now, which is sort of essential – especially when you have boosted power to well over 300bhp and made the thing corner so flat, fast and hard and you live in an area where the next blind bend is likely to be hiding a piece of heavy farm machinery, on a wet, muddy road. Great job Tarox – fitting perfectly, operating sweetly and even looking fab.

So, a huge success for all three products, so bravo to Powerflex, Whiteline and Tarox. And thanks again to Dave at Hesntead for his ace work.

Naturally, as with everything we fit, we will report back with a long term road and full chat track test very soon, here and via

And you can follow progress on Facebook too at: &

Next up, we’re off to our pals at NUR Motorsport (, to make the most of the Bilstein coilovers, Powerflex suspension bushes and Whiteline swaybar, with a full laser alignment and corner weighting. You can read all about that here and on our blog and social media soon…

And with power levels up, stopping power sorted, handling optimised… time for some new rims to smarten her up? Bit of a bodywork clean-up? Or maybe hybridise the twin turbos and upgrade the manifolds? Or… the single turbo conversion Laurence from showed me this week?! What??! Once a turbo nutter, always a turbo nutter! And with that sweet Cosworth V6 under the bonnet, it seems a shame not to make it sing sweeter and to the tune of 400-500+bhp. Right?