Do I have to wait until my car is broken in (1200 mi) to install the new exhaust on it?

No you dont. Just follow same break-in.

Thanks for the fast reply.

If i was u i would wait, its tempting enough to beat on it during the break in period, and i think an exhaust would make it even more tempting...

doesnt really matter

I've been good so far (~400 mi), but you are probably right about me beating on it with the exhaust. We will see. I am still trying to find the exhaust i want .

Take your time looking there are many options available.
In my opinion the creme-de-la-creme is the Fujitsubo but pricey.
Even though you will be fine, if your like me, I would wait for the break-in period since I would not be able to wait to get on it!