Here's what the inside of the stock exhaust looks like on a 2000 Elantra. This is the section right after the small muffler that is immediately behind the cat. It is not really a resonator as it has no baffles or holes inside of it. The inside diameter is only 1 3/8 inches.

 

WTF, did they do that for backpressure/low end torque? eek.gif

 

I can tell you that it certainly wasn't for noise reduction as even with the straight through 2 1/4 pipe going into the stock muffler I cannot notice any change in sound!
It would appear that it is for low end torque as I can feel a loss of low end grunt but the engine now pulls nice and strong right to redline and I can still chirp the tires in 2nd gear.

 

Here in make money off the poor California we have two cats and one resontor mine was right after the second cat but it looks like you have two. But that was on the 2k Tibs I don't know if the Elantra's are the same.

 

what if I didn't have CAT or REsonator and have straight piping and muffler?? too loud?

 

Depends on which muffler you use and if you have headers on. With a flowmaster muffler, yes, that will be too loud.

 

Yea I notice a loss of low end torque also, my engine doesn't seem to pull worth sh^t untill it gets to 3500-400 rpm and then it revs like crazy.