Its a very tinny cricket type noise, fast high pitched tap. Exhaust/gasket issues emmit all of wierd noises but not what we heard on Sunday...

Hi mate. Thats exactly what an exhaust gasket leak sounds like. It sounded very metallic. I couldnt believe it when i found out it was the exhaust gasket. Sounds nothing like a blow from he main pipe. Its worth whipping the manifold and dp off surely if the next option is to break it.