What temp thermostat should i put in my car?

you can use the "orifice plate" that he is referring to or go with a 160 tstat.

it really depends upon how cool you are staying now. you can take two similar stangs and one will run a bit hotter than the next (depending upon previous maintenance, age of parts, etc).
so if you have a 180 now, and run kinda hot, you *could* try a 160. if being in closed loop is a concern, i believe the puter needs to see temps around 178*....

but if you are runnin nice and cool already, a 180 should be good. im sure it is the plan already, but i highly recommend a performance stat like a Mr G. it blows parts store units away.

good luck and enjoy the new parts, Derek.