What happens when you replace ‘ that’ exhaust?
We fit a slip-on Yoshi to find out 1
Suzuki’s new GSX-R1000R might have a new chassis, a swathe of electronic rider aids and clever VVT motor, but when it was finally unveiled, all the talk was about its humungous silencer. It had to go and in its place I’ve fitted a Yoshimura Titanium R-11sq slip-on race can (£734 www.performanceparts-ltd. com). But to see how much difference it would make to performance, I first took my Suzuki to Geoff and Mark at Hilltop Motorcycles (www. hilltopmotorcycles.co.uk) to see what power it makes in standard trim on their Dyna Pro ram-air dyno.
How much power does it make out of the box? 181bhp, with an impressively smooth spread of power and torque. The fuel mixture is bangon although on the road it’s snatchy off a closed throttle at low revs.
And with the can? With the 1.2kg lighter Yoshi can power increases to 188bhp, but the engine runs lean, losing a chunk of midrange. It sounds fruitier, but not too loud (96db@5500rpm on Brands Hatch’s noise meter without the baffle).
What about the fuelling? The final piece of the jigsaw is to alter the fuelling. Hilltop write their own maps, which they load into the standard ECU. Taking readings from Suzuki’s airflow sensor the mapping is self-learning and can constantly change the fuelling depending on conditions.
With the mapping complete power remains at 188bhp, but the stock power curve and fuelling returns, giving you the best of both worlds: elastic power low down and a searing top end. The throttle pick up has improved, but it still comes in too harshly especially in low speed corners in track.
What all this proves is that firstly the standard can may look ugly, but it works brilliantly. It doesn’t contain any Euro4 gubbins, just cleverly routed, silencing tubes, so it’s not heavy, either.
Secondly, if you’re going to fit a slipon can, you may unleash more power, but you’re likely to mess up the engine’s everyday road manners.