VAG S4 & S5: Ring Masters

Audi has been very astute in the positioning of their S and RS variants, offering enthusiasts two levels of engine and chassis upgrades over and above their standard range.

The B6/B7 versions of the S4 used the 344hp naturally aspirated 4.2 litre V8 motor from the A8, but with the B8 S4, Audi downsized to a lighter and more efficient supercharged 3.0-litre V6.

Despite the loss of 11hp, this 333hp forced-aspirated motor provides 440Nm of torque from 2,900 to 5,300rpm, giving it a much better spread of muscle overall than the 410Nm at 3,500rpm of the five-valves-per-cylinder V8, along with potentially better fuel economy.

Apart from having a more lively character than the old 40-valve V8, the supercharged V6 is also eminently more tuneable, with reliable outputs of up to 425hp possible from the basic intake, exhaust and ECU modifications. As this engine also powers the S5, the owners of both types share a common upgrade path.

This is the story of an S4 and an S5 whose owners have taken their cars a big step forwards toward the output of the current 450hp V8-powered RS4. Significantly, the intake, exhaust and ECU tweaks made to the supercharged 3.0 litre V6 engine give it a unique appeal, and the delightful howl of this engine in full battle cry is really quite addictive.

Audi S4

A couple of years ago, Jason Yeo, senior manager at a high pressure laminating company, went to visit a client in the Toh Guan Road East Enterprise Hub.

Little did he know at the time how far things would eventually go when he then dropped in on Audi service and tuning specialist, VAG Singapore, who happened to be in the same building.

“I had owned the S4 for over a year at the time, and while it was a nice overall package I was yearning for a bit more in some areas of its performance, plus it also looked a bit too understated,” he recalled.

“I noticed that VAG’s co-owners Darren and Eugene were smiling and giving me knowing looks as we discussed these points,” he said. “It became pretty obvious that they had heard this all before from other customers.”

Giving the S4 a more purposeful look was easy. VAG Singapore specialise in face-lifting cars using original Audi parts, which they know will fit perfectly. Thus, the S4 was treated to the later style headlamps, and their related ECU re-coding.

For body styling, VAG favour the subtle looks of the Belgian-made Caractere kits and swear by the OE quality of their resilient PU-RIM mouldings. “We don’t like fibre-glass kits as fit and finish is generally problematic and the material also cracks easily if you have a small parking knock,” said Eugene.

The Caractere kit for the S4 consists of new front and rear bumpers and side skirts, and these parts simply replaced the standard ones using the original attachment points.

CarCrafters, VAG’s in-house body shop modified the bonnet with custom vents that help to draw excess heat from the engine bay. Their form follows function aspect also adds to the cars tougher image.

H&R 30mm and 24mm diameter hollow anti-roll bars on the front and rear axles reduce roll to make the most of the wider tyres and the traction of the quattro system. The suspension was uprated with a KW V3 coil-over kit, which offers height adjustment as well as independently adjustable bounce and rebound control.

“Although the KW’s provide much better handling than stock I have had some quality control issues with persistent squeaking noises,” said Jason. “As I am also looking for a bit more ride comfort, I am planning to replace the KWs with the Bilstein B16 kit, which has electronic ride control.”

With the S4’s ride height 30mm lower than stock, the wheel arches are nicely filled out by a set of TSW Bathurst forged alloy wheels in 9.0J x 20-inch, shod with 255/30ZR20 Michelins. This combination gives the car its mean and muscular stance.

Behind the graphite coloured multi-spoke wheels the stopping arrangements are taken care of by RS eight-pot monoblock calipers clamping 365 x 34mm wave shaped RS5 floating cross-drilled vented discs in front. The matching 330 x 22mm cross-drilled vented wave discs come from ECS in the US.

With the suspension, wheels and brakes taken care of, the VAG Singapore engineers turned their attention to the supercharged V6 motor. Their proprietary Stage 1 conversion, which delivers 425hp with 515 Nm of torque, a useful increase of 92hp and 75Nm.

A REVO air intake system helps the engine ingest cool ram air, while an MTM stainless steel sport exhaust reduces backpressure. Although these hardware mods only add a few extra horses, they do help the engine breathe better and respond more crisply to a demand for action.

There is certainly no denying that the soundtrack is improved, and the more bass profundo growl from the sport exhaust underpins the ripping silk scream of the V6, overlaid by the distinctive whine of the supercharger at high revs.

Audi S5

Lucas, the owner of the Malaysian registered S5 is also an Audi enthusiast, albeit not as hard-core or as technically inclined as Jason. Even so he know what he likes and has spared no expense to achieve it.

Like Jason he was impressed with the basic car but wanted more. “It was a fast car but the power soon became too ‘normal’ and I had to have more,” he said.

“I love the S5 because it looks sporty and yet is practical enough for my business use,” he explained.” It is a fast and comfortable car for long distance work on the Malaysian highways, and as he comes to Singapore on business quite often, having the car modified there was not an issue.

Having learned of VAG’s good reputation he visited the workshop and was keen to hear their suggestions. “We sat down and discussed all the possible options for the upgrade work from their extensive menu,” he said. The discussion ended with a bucket list that started with the same Stage 1 engine conversion as Jason’s S4.

However, as Lucas did not want too much mechanical noise filtering into the cabin of his long distance transport, he opted for the AWE Carbon S-Flo air intake system instead. This flows more air than stock but is a lot more aurally subdued than the open filter used on the REVO system.

A full Milltek stainless steel sport exhaust with larger downpipe was fitted, and its reduced backpressure increases efficiency at low engine speeds especially.

To maximise the newfound engine output VAG calibrated the performance parameters of the twin-clutch gearbox, resulting in better response to the paddle in manual mode, faster shifting and increased torque transference.

Lucas was also impressed by the classy design of Caractere’s styling components but in the end opted just for their front bumper and the bespoke hand-formed CarCrafters front wheel arch side vents that are a VAG Singapore trademark.

While the rear bumper remains standard, Lucas opted for the RennTech sequential lights that work the LED turn signal as on the latest factory Audi models. A finishing exterior touch is the chrome look mirror covers.

Suspension upgrades centre around KW’s V3 coil-over kit, set to drop ride height by 30mm. To compensate for the increased negative camber, which leads to excessive inner tyre tread wear, SPC adjustable upper control arms were fitted and the suspension geometry re-adjusted accordingly. VAG also fitted 034 Motorsport transmission and rear differential mounts to limit the movement of these components under torque loading.

With the much higher speeds attainable on the open roads in Malaysia, Lucas considered the brake upgrade a must and happily added the expensive RS6 front and rear brakes to his list of must-haves.

These brakes use 390mm front discs with six-pot calipers and 350mm rear discs with four-pot calipers and stop the car with real resolve. They also look good behind the double spokes of the star-shaped 9.0J x 20-inch BC Forged alloy wheels, which are shod with 275/30ZR20 N’Fera SU1 tyres.

Given their similar engine specs, it was interesting to compare the feel of these two cars on the road. Subjectively, the S5 seems to have better step off, with slightly better low-end punch. Then the S4 comes into it’s own and slowly catches up with its better top end power.

The full Milltek system on the S5 with its tuned downpipe is probably responsible for its better low-end torque when compared to the MTM back boxes on the S4. But there is no doubt that the deeper induction roar of the S4 makes it the more entertaining car to drive, and its uprated anti-roll bars make it feel even more planted in fast corners.

So are these two owners finished with their respective projects? Lucas is happy with his S5 for the time being, but Jason has a list of planned tweaks that include a front strut brace, anti-roll bar end links, uprated transmission and rear differential carrier mounts, and adjustable upper control arms.

Both these cars are fine examples of the work VAG Singapore can carry out on an Audi S model to make it more individual. In the end, how far you go with your car is down to enthusiasm, money, and just how tightly focused a driving experience you seek.