this olympus stereo mic on gopro hero2 = pretty good.
still has the faint AGC repetitive clicking noise floor in very quiet passages (completely gone when i use tascam), but for normal recording especially for car with exhaust, i think the audio can overwhelm the faint clicking noise. it is at least 3dB louder and more dynamic than the real sony mic...
so looks like i need to buy another dead cat cause the olympus is smaller damn... lol i will see if my wife can give me some cloth to lessen the gap inside the windcutter.
Amazon.com: Olympus ME-51S Stereo Microphone: Electronics
Amazon.com: Sony ECM-DS70P Electret Condenser Stereo Microphone: Electronics