I would be more interested to know where the mot centre got an original noise level reading for a granada with a yb fitted from?

Can you shed any more info on :- What sort of meter did they use? what wheighting? what angle,distance,revs did they use to test? what was was the ambient db level?

Not wishing to start any kind of argument just very interested to know high the noise level must have been to cause a fail and how it was mearured?

Most of our hotrod's run v8's with straight through 3"or 4" pipes and have never come across any issues. A couple of our guys are RPU officers and have no guidelines as to any specific allowable levels for road use.