Blah, just get a 3" catted ZZPerformance downpipe from...

ZZPerformance | 3800 Performance Parts | Largest Aftermarket Supplier!

It's all bolt-in..meaning no modifications are needing to be made from the manifolds to the catback...you just yank out the factory one and toss the larger, free-er flowing, better performing, better MPG getting, 3" unit. For the price you really can't beat it...like $180~ bucks.