Exhaust Options for 07+ Sedans

[whatwei]

I realize this may be a repost, but I have saved just enough money for an exhaust & I'm ready to buy so I did some searching and did not find the exact answers I was looking for

1) mainly outside of the stillen & borla exhaust what are the gains associated with the (if no one knows, I will just contact them)

a) tanabe medallionb) hks hi powerc) fast intentions

2) I realize that the tanabe medallion and hks may not be full exhaust systems, but I would consider an HFC for my next mod and probably something else (some other pipe) to complete an exhaust system?

3) Also, while turbo-ing the sedan would be a long ways away (like 3 years), what exhaust system would be best suited for FI?

4) Any idea where I can get the said exhaust systems for cheapest? Anyone got any hook ups they'd be willing to share?

Any help would be appreciated, thanks in advance!