Bear and I may not agree on everything related to this topic, however, one thing we can agree on is that it is a topic which has been thoroughly discussed. A simple search will give you a nights worth of reading. See Nordic Kat's sticky for searching. Good luck.
Originally Posted by bear-avhistory
COBB or the JB4 are the two best choices. Do a search in this forum there are plenty of threads on this question
2009 335i e92
2013 Porsche Boxster S