Need some advice from S650 owners running a Borla S-Type

[Addy]

I recently had a Borla S-Type cat-back installed on my 2026 Mustang GT (non-active exhaust). During the first day or two, I noticed a fairly noticeable low-frequency vibration in the cabin. After 2-3 days, it has improved quite a bit, but I can still feel a mild vibration.

Here's what I'm experiencing:

• Mainly around 1,600–1,900 RPM.
• Most noticeable under load (when accelerating after slowing down or rolling back into the throttle).
• I feel it mostly through the floor and center console, with a slight vibration in the seat.
• On the highway, I can hear a low-frequency hum in the cabin.(without music but not bad)
• No metallic rattles, clunks, or scraping noises.
• The mirror only vibrates very occasionally, not constantly.(if revved really aggressively above 5k)

For those of you with the same setup:

• Is this normal behavior for the Borla S-Type on the S650?
• Did your exhaust mellow out after a few hundred miles?
• Or does this sound like something that could be improved by checking the exhaust alignment or hanger preload?

I'd appreciate hearing from anyone with firsthand experience. Thanks!

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[Jirees98]

I have same setup and never experienced what you described. I'd go back to whoever installed it and let them check it, something might be loose, not sure.

 

[Will2]

Hmm that happens to be the exact RPM range of the loudest drone on various exhaust systems in Mustang GTs, probably a result of the engine hitting just the right resonance at that RPM or something.

So it might be normal to some degree, but if it's causing significant vibration that bothers you, might want to check everything's tight

 

[24CTDH]

how do you guys like the Borla set up vs the stock sound?

 

[Jirees98]

how do you guys like the Borla set up vs the stock sound?

Love it! Sounds deeper and louder than stock for sure! more sporty.

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