[savannahz]

Hey,

When I start my car first thing in the morning and drive for roughly a mile my exhaust note changes and the car kind of opens up a little. it's a very noticeable sound and feel.

Does this happen to anyone else? I'm running mhd 2+ with all supporting mods.

The only thing I have going on is some oxygen sensor shadow codes I'm going to try and work through here shortly. The car is running great.

I do have the emissions cold start reduction enabled via mhd.

Thanks

[IllSic_Design]

If you are catless those shadow o2 codes are normal and will never go away unless cats are put back on.

[OregonDude]

Most likely the sound change you mention is due to the exhaust flap in the left muffler. Search for "Golf Tee Mod" if you want this flap to be open at all times.

[Jklad]

Yes it's normal

[studio54]

The exhaust and everything is cold, so the tone is different.. i like the sound of the first miles

[-JrHatch-]

ive always noticed this, also mhd stage 2+
About 4 or so minutes into my drive the car gets much louder and when it backfires its like gun shots lol, only lasts a few seconds tho
kinda wish it always sounded this way, thing sounds like a beast haha

[-JrHatch-]

Also, its not the exhaust flap, not for me at least, mine has golf tee mod

[4 Doors]

Originally Posted by OregonDude

Most likely the sound change you mention is due to the exhaust flap in the left muffler. Search for "Golf Tee Mod" if you want this flap to be open at all times.

+1

Once the car reaches optimal operating warmup temp, the backpressure/exhaust flap opens creating a noticeable louder sound.

An example of this can be when you cold start your car. Then let it 'warmup' once the RPMs drop, you will notice the exhaust flap opens and the sound is different.

[msjt]

It's also due to wastegate position.

[CanadianTSi]

Originally Posted by msjt

It's also due to wastegate position.

^^^^^^^^This.

[Jeff@TopGearSolutions]

Originally Posted by msjt

It's also due to wastegate position.

This is the correct answer. Waste gate position changes as the vehicle warms up. The louder is exhaust is wastegates full open. The exhaust gets quieter as the wastegates close (warm up).

It's not the exhaust flap as this happens with a golf tee mod or other exhaust flap mods.

[Masher]

You can get a jb4 to set wastegate to fully open when you want the nice exhaust note.

Or if you have MHD just test with the boost lag setting. ull have a little bit of lag but once u find the sweet spot with your throttle youll know when boost activates and when it doesnt.

More boost lag = more open waste gates = more of that beauuuutiful exhaust note