Paulyy

4300 rpm is where it gets measured at on a 1986 944 turbo

the mice was ~800mm away at a ~45 degree angle

thingo

So have you thought of trying one of those right angle tips to aim the exhaust outlet to the ground? Is it bass or treble that is louder?

Paulyy

at 4k rpm no load it sounded more treble. on load it's very deep.

a friend of mine has a race car and he also said they pass the noise by pointing the exhaust down.

it might be worth pointing it down to pass it?

reno want's a vid so i'll upload a drive by possibly tomorrow or something.

thingo

I think it would be worthwhile trying a 'turn down' or whatever they are called, 8db is a fair bit to lose. If it is treble you are controlling even more so, (more directional)and really pretty easy to try.

OZ951

I'm amazed that the maximum allowable noise levels are that low. My 996 has been noise tested a couple of dozen times at track days and its usually 100-101dB at 5000rpm/1m, I pass the track noise limits of 105 easily but stock 997 GT3s often fail, ie >105dB.

thingo

100db at 1m 5000rpm is really not a lot different to 98 at 800mm at 4300rpm. The angle of the mic and the surroundings can have a big influence, and of course it is Paulyy's age that has made the test a requirement. When i see a cop it must be the only time I feel lucky I am old!

OZ951

Probably true, I never got pulled over in the couple of years that I was driving Paulyy's car before it became his car.

Paulyy

It's not difficult to do either. so it might be an option. i'm going to call back the guy who ran the last tests for me and talk through ways of making it quieter.

it's a bit silly IMO, when the new C63AMG merc exceeds the 90db level with a stock exhaust and the Jaguar XKR-S at higher rpm the active exhaust activates and becomes as loud as my car previously before adding the extra muffler.

My age has a lot to do with why i get pulled over and the car has a lot to do with my they aren't sure what is legal and what isn't.
last time the cop asked if it was a 928...

Well difference being i've got a 3" turbo back exhaust with 1 small borla Xr-1 and that's it. & Having a large .82 turbine housing doesn't help with quietening down the noise.

White_951

I know a few guys that have to put a downpipe extension on their exhaust at the track...points sound into the ground...seems to work....

Paulyy

Problem solved. Good bloke behind the counter is just going to write up a pass for me.

Paulyy

i spoke to him about a pipe pointing down, he said that's pretty pointless..

Well i passed at 88db... on the sheet, but just need to be light footed around police which i usually do, which is how i had literally a straight pipe at ~105+db.

951pcarguy

I told the guys at SSI Motorsports in Towson, MD to make my 951 sound like a GT3, so they installed a full 3" SS race exhaust, and it's totally badass now. I drove parts of the Baltimore Grand Prix yesterday at full throttle at 5K RPM and it was glorious.

Seriously, I need to lose a few decibels for the street, so given that I have a V-Band, can I cut the exhaust and add a second muffler and V-Band where the Cat used to be?

Jay

Paulyy

that's what i did. i got the longest and fattest i could find 5" round and 16" long SS muffler