I have a 2009 WRX and I'm looking to purchase a stage 2 kit from either Perrin or Cobb. I was wondering if there was a big difference between the two companies. If so what are the advantages between the two and which one is better in your opinion.
Also in a exhaust system for this car do you suggest 2.5 inch piping or 3 inch? Thanks for any help I get guys.