The Y-pipe is great.
I was told by someone that the cats are good enough until 500HP or so, not too sure on that but Magnaflow makes a high flow cat replacement setup with a good Y built in. Here it is..... http://www.magnaflow.com/02catalytic...irectfit=49664
This would be great with shorty headers, not sure if anyone makes them. Then weld a new muffler in, delete resonators if you want and you are done!
American Racing Headers makes a long tube setup with high flow cats or no cats and a smooth Y-pipe all in one! They did group buy pricing for the forum, probably still good deals. Then do your catback or replacement muffler.
You could make your own setup like I did
This all should get you started! I'm in OKC too if you need help or want to know where the good exhaust shop is!