Could changing the exhaust mess with idle RPM?

[mikenavy]

I changed from the stock to the SLP Axleback loudmouth exhaust yesterday. And noticed on cold startup the RPM fluctuates a lot for a bit, then eventually settles down at 800ish. Is the initial fluctuation due to the car sitting in the cold overnight?

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[10GTSTANG]

The new exhaust probably will not effect cold idle, it probably more pronunced now, shipmate.

[mikenavy]

Thanks for the warm welcome, glad to be around other service members!
As with the exhaust, I see what you mean, with a louder exhaust it is much easier to hear the small changes in RPM.

This is my first Mustang, and first manual car as a matter of fact. And I'm savoring every second of it, I love it.

[WeinerDog]

What you are describing is normal. When the engine is cold, it will idle at around 1100-1200 for a bit and then should settle around 700-800.

And yes, these cars are addictive!

[skyboss_4evr]

Nothing beats the sound of a bad A&& exhaust at cold start!

[wilkinda]

Originally Posted by skyboss_4evr

Nothing beats the sound of a bad A&& exhaust at cold start!

I 2nd that..although my neighbors will disagree

[mikenavy]

Originally Posted by WeinerDog

What you are describing is normal. When the engine is cold, it will idle at around 1100-1200 for a bit and then should settle around 700-800.

And yes, these cars are addictive!

Yeah you described exactly what happen. I guess I've just never noticed it do that.

[discodave]

I had Boomtubes (axle back) put on a few days ago and it sounds amazing.... Question though..... Now I'm hearing a high pitched squeek every now and then and I think it's being caused by vibration. It seems to be coming from the passenger side rear. Any ideas what it could be?

[mikenavy]

I'd get under your car and take a look at it, make sure the hangers are holding the exhaust in tight and it has no wiggle room.