How to silence a decatted/Tubi'd 355 for trackdays?

[jjustin]

Does anyone have any ideas on how to silence a decatted/tubi'd 355 for trackdays?

I've just got a sound meter and at 3/4 throttle I'm running at about 111DB, and the noise limit for a static test at my local track (Snetterton) is 105DB.

Basically, I need to try and quieten it down by 6DB.

The car is booked in for an MOT on Friday and the cats will go back on for that, so I'm hoping that'll quieten it down by a few DB.

If that doesn't quieten down by 6DB (and I don't think it will), what else can I do? I've searched everywhere online for a solution without success. I can't slide one of those baffles into the tailpipes because they're not straight.

How about the exhaust bypass valve? Can that be forced to stay shut somehow to help quieten it down?

Any ideas would be appreciated

[dannylt]

Decat will certainly help a lot; might surprise you how much. I have never seen Snetterton get out their noise meter either. Have a word with the organiser to find out if they have a meter, and don't let rip next to it? Put the standard exhaust back on?

[monge2]

Easy....Do a noisy day at Silverstone and get friendly with the man in the garage
www.goldtrack.co.uk

[jjustin]

All sorted now chaps

I've disconnected the vacuum for the exhaust bypass valve which should keep it shut and reduce the noise slightly, and I've just found a local company who can fabricate me a device that incorporates a couple of supertrap disk silencers that will bolt onto the tailpipes.

I'll post some pics next week when it's done.

[jjustin]

dannylt said:

I have never seen Snetterton get out their noise meter either.

Me neither, and I do loads of bike track days there.
I'd prefer to go prepared just in case, rather than get turned away for being too noisy.

[ferrari355gtb]

jjustin said:

All sorted now chaps I've disconnected the vacuum for the exhaust bypass valve which should keep it shut and reduce the noise slightly, and I've just found a local company who can fabricate me a device that incorporates a couple of supertrap disk silencers that will bolt onto the tailpipes. I'll post some pics next week when it's done.

I think dis-connecting the vaccum will open the valves permanently