The straight pipe is from their E370 and T370 exhaust system that connects onto the resonated X chamber.

Thanks everybody,

Finally I got the answer back with apologieses and saying that The new Straight pipe (correct one) is on the way. They also gave me a track number.
Looks like they care about customers, coz they don't say anything about additional pay for pipe or shipping.
I really thought about 2 bolt type flange install.

Do justify all details about your order guys, whenever you purchase from them, just to avoid same mishap.