where can i purchase straight pipes

Why don't you just take the car to an exhaust shop and let them custom make your pipes. It may be cheaper in the long run.

In my opinion, strait pipes will be obnoxiously loud and will not have a good tone at all. It will sound like the typical "gray primered ******* truck". If money allows, install a new midpipe with or without converters, and a good catback system. Believe it or not, just changing the mid pipe, even if it has a single hi flow converter, will make the world of difference in sound and power. The factory midpipe is the most restrictive thing on the car as well as sound deadening.

In your case, since the laws in your state are strict with cats, get a new catted midpipe (like what UPR sells)to stay legal, then get an SLP LM1 or LM2 catback system.