Any price
Depends, what do you want out of it? Best HP/torque? Loud? Not too loud? Looks, etc... All depends -- I have the SLP Dual Dual Exhaust, and like it -- not too obnoxious sounding, which often just attracts unwanted attention (cops).
You definitely want to go with something that has 3in tubing all the way back (even though the stock Y pipe is 2.5", if you ever upgrade to headers and a new Y pipe it'll pay off), other than that, go with whatever you think looks/sounds the best.
I went with pace setter headers and the pace setter Y-Pipe. Then I went with the magnaflow exhaust. Installation was no cakewalk. The headers will not go on with the engine on the motormounts. I pulled the engine out the top(yes it fits), and tied the headers to the side while I fanagled the engine back in place then tightened the bolts to spec. The rest of it was really easy. I have heard several different exhaust combinations on the LT1 and LS1, and I like the way mine sounds the best. It has a good low tone, I also have a heavily modified engine though.I agree with the response aboutnot drawing too much negative attention,if you want some serious sound (when the time is right) buy some cutouts.
Oh, and to further modify my post, if I were to go for any price for a full exhaust I'd have almost exactly what I have now. The only difference I'd make to my system is a fully mandrel bent mid-pipe that's a little more gracefully integrated onto my Y pipe. I wouldn't change the way my car sounds at all.



