Exhaust reducer sleeves 135i > 125i diameter

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Mike_RS
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Exhaust reducer sleeves 135i > 125i diameter

Post by Mike_RS » Sat Dec 09, 2017 5:14 pm

I've got a Performance exhaust from my e82 125i and I was hoping to install this on my 135i. The 125i has a 2.5" diameter pipe and the 135 a 2.75" pipe, I was considering using an adapter to mate the two.

I know this inducing a very slight restriction just before the back box but it's only a 7mm step down and the fact the performance back box is a freer flowing box in comparison to the stock 135i back box would surely counteract any added back pressure by the adapter?

I know in an ideal world i should just get the 135i version which is 2.75 straight through. I'm not really looking to add performance by doing this, just a little more sound and get rid of the stock looking pipes until I eventually buy the 135i version later in the year.

Am I going to do any damage running a 7mm step down?
Black sapphire metallic - E82 N55 135i - BMWP Exhaust - Suspension - Brakes - Carbon Mirrors- 18" 313 wheels with PS4's - Wagner DP - LED Darklines

Mike_RS
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Re: Exhaust reducer sleeves 135i > 125i diameter

Post by Mike_RS » Sun Dec 17, 2017 8:55 am

Turns out the 125i performance exhaust is exactly the same for the 135i! There is reducer pipe welded into the muffler to reduce the pipework to 2.5" to marry up to the 125i mid section. I'm going to cut out the 2.5" (63mm) pipe and weld in a 2.75" (70mm) which will then marry up perfectly to the 135i mid section with no restriction.

I'm going to start a separate thread on the project if anybody is interested :headbanger:
Black sapphire metallic - E82 N55 135i - BMWP Exhaust - Suspension - Brakes - Carbon Mirrors- 18" 313 wheels with PS4's - Wagner DP - LED Darklines

Fritz
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Re: Exhaust reducer sleeves 135i > 125i diameter

Post by Fritz » Sun Dec 31, 2017 12:24 am

Hi Mike, just wanted to say you've helped me with some info on my 135i backbox to 130i mid section with the diameter info best of luck with the upgrade!


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Mike_RS
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Re: Exhaust reducer sleeves 135i > 125i diameter

Post by Mike_RS » Sun Dec 31, 2017 3:33 pm

Glad I could help! :D
Black sapphire metallic - E82 N55 135i - BMWP Exhaust - Suspension - Brakes - Carbon Mirrors- 18" 313 wheels with PS4's - Wagner DP - LED Darklines

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