After finishing the 2012 Sport Auto High Performance Days as the fastest car in the street-legal supercar class, we decided to take a closer look at both the MTM McLaren MP4-12C in particular, and MP4 tuning in general.

The tuning scene for this British sports car is relatively new, and yet anybody who attended this year’s Geneva Auto Show would be very aware the most popular tuned cars were the new Porsche 911 Carrera and the McLaren.

Although new to the scene, the turbocharged MP4-12C is the more likely candidate, and all examples on display had ECU and exhaust upgrades claimed to contribute a further 70-80hp to the head count.

The MTM version we’re driving uses the company’s M-Cantronic system plus a larger downpipe with 200-cell metal cat. Together, they boost output to 680hp at 7500rpm, with 480 lb-ft of torque from 3100-6500rpm. This represents a significant increase over the stock motor that has 592hp at 7000rpm and 440 lb-ft from 3000-7000rpm.

“The ECU remapping is done with our Cantronic piggyback ECU,” Roland Mayer from MTM explained. “It transmits the right signals to the McLaren ECU so it thinks everything is normal and won’t throw any engine check lights or go into limp mode.

“We experimented with 100 and 200-cell metal cats, settling on the latter to achieve the emissions target. The reduced back pressure from our new downpipe and catalytic converter mean the turbo doesn’t spin as fast, reducing the boost pressure.”

“To compensate, we increase boost on the inlet side to achieve the same turbocharger speed as before,” he continued. “Combined with changes to the fuel and ignition maps, the extra boost gave us the power and torque improvement we were looking for. And because the turbo isn’t actually spinning faster, there’s not much extra stress on the components.”

It wasn’t long ago that any road car that could reach 100mph in under 20sec was considered quick, but on a warm summer’s day in Germany we recorded 0-62mph in 3.2sec, with 124mph coming up in 9.3sec in the MTM MP4-12C.

Predictably, traction was an issue when attempting full-bore standing starts and these drag race numbers are similar to the stock cars. But the real improvement is on the fly, where numbers struggle to describe how this car performs when you plant your right foot deep into the carpet.

We had driven a pre-production MP4-12C on a test track more than a year ago and it was quick, but with the wick turned up by MTM, the twin- turbo V8 produces sensational thrust in every gear.

Acceleration from town speeds in second gear is strong, smooth and relentless. And it’s maintained in the successive two gears, where you’re able to exploit the higher 8500rpm rev limit as the engine soars past its peak power at 7500rpm.

Other than its wider wheels, MTM’s McLaren chassis was stock when it ran in the Tuner GP (see report in this issue) but was wearing the tuner’s same lightweight forged wheels that were fitted when we drove it on the road two days before the event.

The staggered set-up used 19x8.5" front and 20x11" rear wheels, wrapped in 235/35 ZR19 and 305/30 ZR20 Michelin Pilot Sport rubber. Despite the car’s success in this guise, the forged wheels were actually a temporary measure until specific forged wheels can be manufactured by BBS.

They might be wider but fortunately the big wheels don’t erode the sedan levels of primary and secondary ride that make the new McLaren sufficiently civilised for daily use.

Despite the wide rubber, we experienced wheelspin in second gear on a dry road under full throttle from 20mph, underlining the exuberant delivery of the mid-range torque.

“We didn’t originally plan to include the McLaren as one of our entries in the Tuner Grand Prix,” said, Roland Mayer. “The car arrived later than expected, and after getting the engine remapped and downpipe fitted, we had no time to optimize the suspension geometry or go testing.

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