Yes. Currently is 2". Gonna sell soon anyway.     

I see, that was what they call trumpet muffler isn't it? So, which type is recommended? Currently, i'm looking for JASMA approved muffler at half-cut but sadly, 2" seems like do not exist at all. Minimum inlet i can find is 2.3".

owh, btw, is there any good immitate stuff out there which is reliable?

Thanks. 

Hey guys, I'm planning to change my exhaust system.

But there is a problem as the extractor I'm getting it from a different shop from the piping and mufflers.

So my question is which do I get it changed first?

Change my extractor then only head to the other shop to change my piping and muffler?

OR

Change my piping and muffler then only head to the other shop to change my extractor?

Which is better? or which will you all choose?

Thanks for the pics!

Flow and CFD happen to be one of things I do for a living, that's why I'm quite interested in how it works, although my skill level is borderline retarded.

Given the Reynolds number of typical exhaust gas (composition tikamed with AGA-8) and the bend factor, I'm not sure how it would increase velocity via the swirl. I guess the velocity would increase from the restriction but the swirl would create more turbulence, sapping it of kinetic energy. But I guess I'm not qualified enough to give a final answer, given the shape of the thing.

Just dreaming of a good exhaust after my friends at CEEFC threw around the idea of a few of us quitting our jobs and building high performance Inconel manifolds and titanium exhausts.

The best way to create backpressure for a system without turbulence or disturbing the pulse or  lamellar flow is with a venturi type of restriction. Preferably cast or machined rather than rough welded.

Hi all Sifu,

my Myvi Gen3 1.5cc  currently change exhaust system.

4-1 Extrator + center muffler +Sflow muffler 

but feel like lack of pickup , how to improve it ?

my travel route mostly highway ,so foremen recommend 4-1 for me ,

what is different between 4-1 and 4-2-1 ?

so far as i know 4-2-1 is for low torque, mean below 4000rpm will get good pick up but cant top speed 160h/km?