90db limit

[saleenr6]

http://www.motorsportreg.com/index.c...8#.VvoigmNh1ZI

How do I know if my E92 M3 with Borla ATAK meets this requirement.??

[roastbeef]

it is really hard to say for sure. i just tracked at laguna seca. i'm not a local, i cam specifically to track my car and i didn't want to get shut down early, so i swapped my oem exhaust back on. some rear sections can be very loud, my vorsteiner rear section is moderately loud. it was a pain, but very worth not having to worry about it.

[saleenr6]

Well thats not comforting to know. Hmmmmm I emailed them about it and they told me to measure the db at 50ft. Im like..ehhhh......

[roastbeef]

Originally Posted by saleenr6

Well thats not comforting to know. Hmmmmm I emailed them about it and they told me to measure the db at 50ft. Im like..ehhhh......

keep in mind, the dynamics of the sound change a little bit at the track, you're at wide open throttle, under load (heading up the hill), and your exhaust is going to be as hot as it can get. might be a bit louder than you can get it on the street.

[redpriest]

My friend measured his stock exhaust on the F80 M3 at 7500 RPM in Sport+ from 50 ft. It was 102 db :O 3500 RPM in Sport was 88 dB. There's not a lot of wiggle room.

[roastbeef]

i wish there was a way to find out what i was measuring with my oem exhaust/xpipe.

[saleenr6]

James,

We can't really answer your question. Most aftermarket exhaust will not pass 90 db limit. To make sure you can use a sound tester and measure it from 50ft away.

Patrick Chio
Speed SF Track Events
Speedsf.com


I hope he is right.

[roastbeef]

i just went to laguna seca last weekend and swapped my oem exhuast back on for it. i'm really glad i did. i didn't want to stress about blowing sound and i saw a few people get flagged for it.

its not a frequent trip for me, but you're a bit closer... it wouldn't be fun getting shut down, but with aftermarket exhausts, its sort of a gamble.

[hayes180]

the sound booth is between turn 5 and turn 6 on the right side of the track. 50 feet seems about right. You can ask for a sound test at the track which if you go over will not give you a black flag (2 blag flags for sound done for the day). A few options 1) Go back to OEM 2) Short shift to a higher gear when passing the sound booth 3) Come up with some sort of contraception to reduce the sound (steel wool) 4) Leave it on and floor it by the booth to see if you pass sound or not (using your test run). Simplest to ensure you have no problems is go back to OEM. I've tracked here numerous times and its my "home track" 20 minutes away, OEM is a good way to go. I know for sure that DINAN and AKRA slip ons PASS sound at 90dB.. Hope this helps

[redpriest]

My full akrapovic evolution passed for me - I was worried because I've seen reports where it can be borderline. What I usually did was keep it in 4th while climbing the hill after turn 5, but after a few days and daring the black flag, I was flooring it in 3rd and had no problems.

[roastbeef]

Originally Posted by redpriest

My full akrapovic evolution passed for me - I was worried because I've seen reports where it can be borderline. What I usually did was keep it in 4th while climbing the hill after turn 5, but after a few days and daring the black flag, I was flooring it in 3rd and had no problems.

I can't believe how quiet your car is.