since most all exh systems 4 most of our cars (NA, no boost) usually yield similar results. go after other issues 2 decide. Sound levels? Price? Loox? race header/hi-flo cat/ORP in ur future-thus Sound again? and which sponsor u want 2 buy from.
these and a couple others should b ur main concern. house favorites seem 2 b the bosal, thermal, FS, Magnaflow, MBRP, etc. check out the many threads that addresses many and each of these systems 2 better aide u in ur final choice 4 ur application. this is a pretty broad post, yet realize many will talk up the 1 they have. b mindful of that, but remember its ur application thats important.
lastly, as briefly mentioned above, u have 2 also take into consideration future exhaust work. if u get more aggressive u might want 2 start w/a quieter system 2 avoid the fuzz later. also whether u will consider boost in the future will impact ur decision. good luck.