Barty964rst

I think the 4,800 Rev request must have hit the sweet spot for resonance, hence why it registered so high on the DB reading. On the M40 return I was trying different speeds, gears and rpm ( I was bored) and the 4,800 was uncomfortable to the ears for any lengh of time.

HiWind

Marc's so right re induction noise - put some foam in there and you might just squeeze thru.

BillyB

As another data point, a Decibel Devil (in a round exhaust tip) took me from 109 to 106 db at Bedford on the static test. My set up was g-pipe and decat, although I am now going to fit a standard rear silencer in place of the g-pipe for track days (in fact I will have the rear silence plus round tip as a swappable unit for the g-pipe and oval tip)

boxsey911

According to the owner Jev, who I've met before:

Thanks Boxsey, I baffle and pack both exits for the static test then pull them before I head out on track and never had any hassle with any drive by police.

Hot engine + dipped clutch + a smile a the noise tester usually helps too. My Mrs did the noise test for me this time and I think her smile got her off with a 4200 rev too.

VR6-er

Sorry for the thread hijack. I've got a primary bypass on mine and am adding a decat pipe. Will the decat make it louder?

jevvy964

Thanks again boxsey I tried to help the OP when he was looking for stuff in the motorsport shop at Oulton with the same advice.

As you know the 3.2 runs a 993 3.6 and the exhaust is a magnaflow x-over box which is fairly small and light. It does bang a pop a lot but that doesnt seem to bother the sound tests/meters. It might be worth looking into for you 964 guys as other than flipping the flanges on a set of 993 HE's its a bolt on mod that should win you some power, save some weight, retains the standard heat stuff and also gives you easy baffle and bung options.

Heres a pic of the system before swapped the tailpipes:


And fitted:

Cheeksyboy

Nice 3.2 Jevvy....were you also at Silverstone on Sunday?

Does this go to show that static noise tests bear no relation to actual noise!?

jevvy964

Yeah I popped up to Silverstone on Sunday afternoon too - was good fun but well slippery. I didnt see you, were you playing too?


Static noise tests are certainly harsh on a 911 and I've had a few close shaves over the years. I used to leave the baffles in after the noise test but the wire wool just sets on fire and the baffle inevitably falls out so I just pull them and have never tripped the drive by's. I think the theory of the x-flow box is the sounds from each bank whack into each other and kill some of the volume, heres a vid from when I first fitted it(excuse the tailpipes) - very loud at tickover but as the revs rise the volume seems to drop somewhat.

Andy Roe

Yep!

Cheeksyboy

Nope, was on a tour of the Silverstone facilities (BRDC, Race Control, etc) with a mate....will try and catch up next time I see you out on track!

Agreed. I may have to look into this more

Soz Barty if we've gone a bit

MSH5

Any current simple solutions anyone can suggest. Not looking to change the exhaust, just add a reduction tip or insert a baffle. Car is a standard RS.

BillyB

Decibeldevil. Takes about 3dB off

https://www.driftshop.com/decibel-de...universal.html