As posted on Octane by me.
UPDATE:
I went back to the NCT test centre this evening. I spoke to the manager on the phone first this afternoon and told him my various misgivings about the testing procedure. The way the car was revved. The way it was tested inside beside lots of other noise. The not clearly defined testing procedure. He was actually very nice about it and said I could come in and try it again. He said their "designated sound test area" was actually there in the lane where emissions are tested. In other words, there is no special area I guess. He said they usually rev to between 3500rpm and 3800rpm. He said all he could do was get a supervisor to try it for me.
The guy testing it this time was a South African bloke. He was a sound guy and I asked if he could rev it not so aggressively to try and get a lower reading. He said he'd do it just as per normal. Sure enough he came back out after a couple of revs and showed me the reading 117.2dB.
ARGH.
Then he went back and tried again for about 10 minutes, various revs, some fast, some slow etc. He came back and said there was no chance of getting it lower and it was actually 118dB when he was trying the second time.
So thats it. Game over.
Chatted to him for 10 minutes after that. He told me about a Ferrari that some tester failed on its standard exhaust. 128dB. They had to fail it once it was sound tested. He said that's the problem with mine now. Once its in the system as a fail refusal for noise, they cannot just say its "ok" without getting a good result on the noise test.
Not sure how their sound meters are calibrated. He agreed my car doesn't sound loud but said there is a spike there (the BARRP noise) when revving it thats actually quite loud when your behind it. This BAARP doesn't happen under load while driving by the way, only when revved from idle in neutral.
I've ordered an insertable baffle anyway, and if necessary I'll stuff it full of something or other. The wool of a steel sheep maybe.
My mates gonna lend me a digital sound meter, so I will be able to do a before and after test to see how much dB difference (% rise) the bung makes. That should give me an idea if it will pass the retest. Any interruption of flow in the zigen exhaust might eliminate this BARRP noise. Hopefully. If my own tests don't show a good reduction using the bung I may have to borrow a standard back box and get it replaced for the test. This is a real pain though, ramp time, gaskets, etc, and would need to be done every year for the test. Hopefully the bung with or without steel sheep wool in it will do enough.
Anyway, the point is, the tester guy this time was sound, as was the manager, but the fact I've been sound tested and failed means theres no going back now. I'll have to get it to pass. I don't have any bones to pick with the guys, its a pity my car was highlighted to be checked in the first instance but thats just life. The guy who flagged it prefers testing quiet family cars I guess. The only bones to pick are with the people who forced implementation of this half baked test, probably because some toff complained to his TD friend that some yob in a crap with a huge can was scaring his horse and waking his wife every night by doing laps in the field behind his stud. :'D
When I was there at the test centre tonight, there was a 2007 Merc AMG SL63. It sounded as loud as mine. It wasn't subject to the sound test though. Fair play to the ould lad driving it, he took off up the road outside the test centre. Sounded audacious. lol.
I'll probably update the thread when I get my own sound meter readings with and without the bung. I'll be very interested to see if my reading without bung is 100+dB.