Most parts i think would have a negligable difference between makers.
For instance I would think that the difference between a ms cai and the sri shouldn't be that big of a deal, and will work until you get a custom tune.
I would think that Cobb wouldn't be extremely aggressive with their tune, they probably have a little slack in there that can be fine tuned by each user. Because i think that other factors (elevation/temp), would have a greater affect than MS cai vs Cobb Sri.
If i'm wrong let me know, but both the Cai and Sri essentially do the same thing (more airflow?)?
When looking at exhaust there are different design issues but they all generally do the same thing at the same level. I don't think the subtle differences will be noticed on a stock map.
-mk
not an expert, but did do a lot of chip tuning on a quick little 1.8t Gti, Revo ftw!