I was undermy car the other day looking at the exhaust and I saw that it looks like the pipe coming back from the res. before it gets to where it y's off to the mufflers is 2.5" pipingand after the y it's reduces downto 2.25". Has anyone else saw this?

 

The flow capacity of any pipe is directly proportional to area of the pipe.A 2.5 diameter pipe has an area of 4.91 square inches (pi X dia.squared /4).A 2.25 diameter pipe has an area of 3.976 square inches,times 2 pipes gives a total area behind the "Y" of 7.952 square inches.So the 2 smaller pipes still have more area than the one large pipe,causing no loss of flow capability.

You will be tested on thismaterial next Wednesday.

 

Yes sir, I'll be ready, lol. The reason why I was wondering this is because after I get my muffler put on, some time down the road I want to put a qtp cutout on there and was looking for the right size piping.

 

yeah, on my model the pipe gets smaller after the resonator, and then gets smaller again after the split to dual tips. well, my cat back systen replaced all of this so the pipes are 2.5" all teh way back.