You can have a listen here. Don't be fooled by the invisible car, it was not at a secret test.
"Doing a recording in a test cell is quite challenging because you need to extract the exhaust fumes and extract them safely from the factory that the test cell is within," he said.
"An awful lot of technology goes into making sure these fumes are extracted and filtered, which naturally takes some of the sound with it.
"Then, a test cell is a room with flat walls, which causes the noise to bounce around and reduces the purity of the sound. It's an engine dyno - not a recording studio!"
"We are a good way on and already heavily committed to tooling for long lead-time parts and working on iterations for installation purposes," said Cowell.
"When it comes to development, you have to run your own race. As ever with competitive people, they fight and strive to do as much as possible, focus on the issues that still have to be solved and rarely spend too much time reflecting on the successes."
"On the V8, you've got two tailpipes, so there are four cylinders feeding exhaust pulses into each tailpipe, the crankshaft is rotating at 18,000 rpm and there is no restriction in the exhaust system.
"We put a lot of effort into making sure it's a free-flowing exhaust system and highly tuned because the way to extract performance from a normally aspirated engine is to have highly tuned inlet and exhaust systems.
"On the V6, we have a single exhaust tailpipe, so all six cylinders are ultimately feeding into the single exhaust pipe."However, because the new formula for 2014 is focused on getting the most useful work out of a fixed quantity of fuel at a maximum flow rate, the regulations include the option to have a turbine in the exhaust system, which extracts energy from the exhaust flow to drive a compressor which boosts the inlet charge.
"The turbine also drives an MGU-H (Motor Generator Unit - Heat) for recovering excess energy over what is required for the compressor, which can then be stored in the battery and increase the boosting potential out of the corners.
"As soon as you have any restriction in the exhaust system, you reduce the volume of the noise because the turbine wheel is designed to recover energy from the exhaust flow, which naturally reduces the volume of the noise coming out.
"But because it's six cylinders firing into a single tailpipe, instead of four into each pipe on the current engines, the frequency will be very similar to the current 18,000 rpm.
"So we will have a similar frequency but lower volume because of the energy being recovered from the exhaust stream."