I'm putting this info here for documentation purposes. Someone is gonna ask so this will give them something to go off of. As for the diameter, I used a digital caliper. I would take a measurement, remove it and take another measurement. Then I'd rotate it half a diameter, measure again, remove it then measure again. Your results may vary. I'm not saying this is exact so no argument for me. It'll help me for reference later.




The B pipe inlet diameter (After flange from 2nd cat) and (Before the flange at the muffler) are both the same size. 42.21mm (1.66"). Here are the different outer diameter results I got throughout the B pipe. A picture is provided above but I will type it out below in case the picture does not work in the future for some reason.

Outer Diameter
Pipe after 2nd cat -- 45mm (1.77")
90 degree bend
Pipe leading towards the resonator -- 45mm (1.77")
Bend towards resonator
Inlet piping to resonator -- 44.5mm (1.75")
Resonator
Resonator outlet pipe that has slight bend -- 40mm (1.57")
Piping after slight bend that goes to muffler -- 41.44mm (1.63")

After taking all these measurements, it makes me feel more confident that going to a 50mm (2") piping doesn't seem like that small of a jump in diameter at all. Especially from measuring the piping between the resonator and the muffler. Good luck in whatever you choose to upgrade too. Choose wisely!

Then I weighed the B-pipe on a bathroom scale. The B-Pipe weight is 10.4lbs (4.72kg)

 

2 1/4 straight pipe good for Honda Fit 2002? Noobie here

 

U got me! I've only dealt with the 2015 model.

 

Hi , i took the time when i bought my rv6 header, i own a 2017 GK, to measure its inside diameter since almost always on every brand the advertising diameter is the outside and not the inside which is the one WE want... and i was around 55.11mm or 2 ³/¹⁶" .... which is a little bit les than 2¼ obviously... the axle back i mounted is the tanabe medallion and to my surprise it was around 2⅛... yes...a tiny bit smaller but since it is a straight through exhaust, it doesnt do any harm..... for the "B" pipe or mid pipe, i went with 2¼ straight through and i don't regret it... i love the sound... its a bit loud for some people but I like it.... and performance wise it feels really good and runs a lot more loose... i also have a ktuner installed but im still with the OEM program since the CoViD-19 shit threw my dyno plans to the back burner.....
Hope this info helps

 

Yeah 2.25 is the sweet spot. I have no muffler and 2.25 straight back from the rv6 catted one. I'm gonna put a magnaflow resonator on it to quiet it down a Lil bit.