I made a couple of assumptions using the dimensions and weight of my mid pipe and the OP's exact location in Florida and I came up with an overnight shipping price of $270.I'm kinda surprised you all are blaming the OP. And sure, Texas Speed isn't obligated to overnight the part, but can you imagine how much better it would be for them to have a post about them that says "OMFG these guys ROCK, they shipped the wrong part, everybody makes mistakes but these guys went out of their way and overnighted the correct one so I could get the install finished on schedule. God bless Texas Speed" Instead, the loud and clear message from them is "meh...we screwed up...tough shit. Next?"
On top of this there is also the cost to ship the wrong mid pipe back regular freight which is around $40.00.
Do you expect the vendor to absorb a $310 expense for shipping the wrong part?
If the OP would have opened the box and noticed the wrong parts it would have cost the vendor only $80 to ship the parts both ways by regular ground shipping.
On top of that as a vendor I would either expect the parts back or a deposit on a credit card prior to shipping new parts out.
That's standard business practice.
To be perfectly clear the screw-up of sending out the wrong part is on them.
The screw-up of not checking that the proper parts were received is on him.
The OP should be paying the shipping difference.