question about exhaust

[LPGUTE]

ya hello guy am just woundering when am getting a quote from the exhaust place to get a catback what should i do/ask?
i would
1 what i want (2 1/2" catback).
2 what going to be in it? (muffler, tip ect)
3 price?
is that sould about right?
i got a quote from a place saying they going do custom because it LPG with resanotor at the front and muffler at the back. i think i see people saying dont get resanotor.
so please tell me what i need add extra or any thing else u could think off.
thx