Exclusive: Chevrolet SS goes loud and proud

HOLDEN engineers appear to be testing a bellowing bi-modal exhaust system along with a six-speed manual gearbox and magnetic selective ride control suspension for the upgraded 2015 Chevrolet SS to be launched in North America later this year.

These changes would address perceived deficiencies in the Australian-made export model in the United States where bloggers have been well aware that Holden and its hot shop partner, Holden Special Vehicles (HSV), offer such goodies on the equivalent Australian Commodore sports sedans.

Until now, the production Chev SS has only been available with six-speed automatic transmission, standard gas-damper sports suspension and relatively muted exhaust.

Now, General Motors has let slip news of the gearbox and suspension upgrade in its 2015 model-year online reference guide for US fleet buyers.

The guide also confirms that the manual-equipped SS will get a shorter 3.70 final drive ratio, compared with the automatic’s 3.27 differential, along with a new front registration plate bracket, standard OnStar communication system and some fresh colours.

But what the official GM document does not say is that the Chevrolet SS is likely to get a deep-throated new bi-modal exhaust system that should give the sports sedan greater street cred.

GoAuto can confirm that the Lang Lang bushland around Holden’s Australian proving ground has been ringing with V8 thunder as engineers test the latest SS exhaust that, to our ears, sounds louder than before.

All Australian HSV-enhanced Commodores except for the entry-level ClubSport sedan and Maloo ute already have a bi-modal exhaust that bypasses part of the system for a greater output and beefier note at higher revs.

As the Chev SS is equipped with the same 6.2-litre LS3 V8 engine as the HSV models, it should be a relatively easy modification on the SS.

The current Chev SS pumps out 310kW of power, but a sportier exhaust is likely to increase that, possibly to the 325kW offered by most bi-modal HSV models or even the 340kW on tap from the SV Enhanced models.

With a shorter final drive, manual transmission and – perhaps – more power, the Chev SS is likely to smash its current five-second 0-100km/h sprint time.

The magnetic ride system earmarked for the SS is likely to be the same third-generation Magnetic Ride Control developed by HSV in conjunction with BWI Group for the latest Gen-F HSV Senator Signature, Grange and GTS.

The semi-active suspension system uses magnets to adjust the damping according to sensors in the vehicle, with the driver able to select from two modes – touring and sport. The 430kW supercharged 6.2-litre GTS sports flagship also gets a track setting.

The dual-spring Generation 3 ride system on the HSV Gen-F range is said to respond twice as fast as the previous generation.

The word “selective” in the Chevrolet description of its upcoming new magnetic ride control would indicate that the Chev SS will also get one of these multi-mode systems.

Altogether, the changes to the 2015 Chevrolet SS will help to address beefs from American car fans who have called for the car to be given the full HSV sports treatment.

The slow-selling SS, which managed only 1662 sales in the first half of 2014, was launched in North America in the second half of last year. GM targeted a mere 2000-3000 sales a year, citing the Australian dollar exchange rate as one of the inhibitors to greater export volumes from Holden’s Australian factory at Elizabeth, South Australia.

With the Aussie dollar sitting at about 94 cents to the US greenback, nothing much has changed there.

Like its Australian counterpart, the Commodore, the SS is set to go out of production in Australia by the end of 2017 as GM pulls its manufacturing operations.