[frankshufang]

Anyone has any idea on what's the loudness after a M240i replaced with the Dinan mid pipe and free flow exhaust?

I want to use my car for going to track. But have no idea on if I will fail on the sound restriction.

[NewWorldOrder]

Originally Posted by frankshufang

Anyone has any idea on what's the loudness after a M240i replaced with the Dinan mid pipe and free flow exhaust?

I want to use my car for going to track. But have no idea on if I will fail on the sound restriction.

I have both resonators deleted with the Remus exhaust, and I don't think the car is louder than a stock Mustang GT.

I don't think you have anything to worry about.

[frankshufang]

Originally Posted by NewWorldOrder

I have both resonators deleted with the Remus exhaust, and I don't think the car is louder than a stock Mustang GT.

I don't think you have anything to worry about.

Do you still have the valve after the Remus exhaust installed?

[NewWorldOrder]

Originally Posted by frankshufang

Do you still have the valve after the Remus exhaust installed?

Yes, but it only closes the valve on startup. The valves open up after cold start is done.

[dradernh]

Originally Posted by frankshufang

I want to use my car for going to track. But have no idea on if I will fail on the sound restriction.

What is the sound limit for the track you'll be running on? For example, 87dB.

I'll share with you my experience of running on tracks that had very strict sound limits. One example is a former F1 track where drivers were assured that excess sound readings were relayed in real time to the local police department, and that the department would contact the track after receiving that data. Was that true? Who knows, but it wasn't unusual for black flags to be waved for excessive sound. This is a track where the local residents wish dearly for the track to be closed.

The situation is the same at a non-former F1 track with no pipeline to the local PD, but with local residents who also want the track closed. These examples are from classic and very highly-regarded tracks in the Northeast.

I ran into this while running a race car, and my solution was to carry three mufflers with me. If I was black-flagged during practice with the noisiest muffler, I changed to the next quietest muffler. If that didn't work, I put on the muffler that would pass any test. Dyno testing of the car showed very little difference in rear-wheel horsepower between the three mufflers.

That's all a lead-in to this: you can't tell ahead of time what results your car is going to produce at a given track on a given day. The variables are climatic conditions, placement of the equipment collecting the noise data, and how your car produces sound that might exceed a track's limit (e.g., for a turbo car, pops and burbles after lifting in a braking zone).

For a street car that you want to make louder and still take to the track, your best approach is to ask for advice from the people running the event (hopefully, it's a BMW event, in which case they may have more specific advice to offer you). Whatever advice they give you will be based upon their experience at that track, and that's invaluable. The last thing you want is to discover at the track is that you can't run. Been there, done that – not fun. Plus, the per-lap expense goes right through the roof!

[frankshufang]

Originally Posted by dradernh

What is the sound limit for the track you'll be running on? For example, 87dB.

I'll share with you my experience of running on tracks that had very strict sound limits. One example is a former F1 track where drivers were assured that excess sound readings were relayed in real time to the local police department, and that the department would contact the track after receiving that data. Was that true? Who knows, but it wasn't unusual for black flags to be waved for excessive sound. This is a track where the local residents wish dearly for the track to be closed.

The situation is the same at a non-former F1 track with no pipeline to the local PD, but with local residents who also want the track closed. These examples are from classic and very highly-regarded tracks in the Northeast.

I ran into this while running a race car, and my solution was to carry three mufflers with me. If I was black-flagged during practice with the noisiest muffler, I changed to the next quietest muffler. If that didn't work, I put on the muffler that would pass any test. Dyno testing of the car showed very little difference in rear-wheel horsepower between the three mufflers.

That's all a lead-in to this: you can't tell ahead of time what results your car is going to produce at a given track on a given day. The variables are climatic conditions, placement of the equipment collecting the noise data, and how your car produces sound that might exceed a track's limit (e.g., for a turbo car, pops and burbles after lifting in a braking zone).

For a street car that you want to make louder and still take to the track, your best approach is to ask for advice from the people running the event (hopefully, it's a BMW event, in which case they may have more specific advice to offer you). Whatever advice they give you will be based upon their experience at that track, and that's invaluable. The last thing you want is to discover at the track is that you can't run. Been there, done that – not fun. Plus, the per-lap expense goes right through the roof!

The laguna seca has some 90db or 92db restriction. Also, for the Sonoma raceway, the restriction seems to be 96db. I just don't have the idea how loud my car currently be. So I am not sure what kind of event I can register for.