Anyone know what the OEM exhaust diameters are?

Header - Out ?
Cat - In 2.25 (ID), Out 2.0 (ID)
Front (Y) pipe - In 1.75 (ID), Out 2.375 (ID)
Mid pipe - In 2.5?, Out 2.5?
Muffler - In 2.5?

I currently have Berk HFCs which are listed at 60mm in/out (2.36in) So this means there is a 2.36->1.75 transition from HFC to Y pipe which is bad (from what I've read).

Is there an aftermarket Y pipe that would solve this without causing the same issue at the mid pipe? For example, I believe the MD XYZ pipe is 2.5 in & 3 out. This would cause 3->2.5 transition from mid pipe to muffler.

 

I can tell you the Berk HFC to OEM piping is no problem whatsoever. I don't know the measurements but I and plenty of others have had that and no issues

 

Yeah, I don't have any performance issues either that I'm aware of, but I don't have a reference (i.e. stock) to exhaustively (ha) compare against to know that there may be an issue.

That said, while 2.36->1.75 may be OK, 2.36->2.36/2.5 is empirically better right?

 

Measured my OEM cats: inner diameter appears to be 2.25 inlet and 2.0 outlet.

 

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