When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Search around a bit on the tech forum and you will find almost every combo has been tried.
The stock cat back is very efficient and should be left alone if only looking for power gains. The best bang for the buck so far seems to be the long tube headers and a CAI, I personally like the vararam.
After that its onto heads/cam for really good gains N/A, and thats quite a hotly debated topic with quite a few good combos out there.
Most start with CAI and exhaust. Make sure you do plenty of research on the exhaust though. Most of them are much louder inside the car and many don't like it especially with headers. CAI can yield 15hp. Exhaust gives 4hp and header gives 20hp. Headers needs tune.
I think you've received some good suggestions. IMHO I'd concentrate on building a strong naturally aspirated engine instead of changing the rear end gearing.