I wouldn't get too hyped up for Big Name exhaust, min gains I see no prob going w/ a budget company like Megan as far as catback. The boxer engine sounds near same no muffler/ $1k catback, very close tone a matter of a little muffled or race car sound. That is one plus w/ Boxer engine, unlike a Civic where you MUST have a nice catback, this engine isn't soo picky as far exhaust sound goes.
I personally would rather spend $$$ where it matters most for gains, instead of Expensive catbacks on N/A car. Now on the Boosted car, Exhaust is HUGE and get some gains, then a $1k Catback isn't soo bad, but for FR-S I'd rather save money on a catback and put extra $$$ and do handling like wheels/tires/suspension.
More options the better ! More we have to choose from!
My .02 cents!
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Autocross & Drift = my Anti Drug!!
I have Car A.D.D prior few:
12' Evo GSR, 13' FR-S, 11' STi, 08' 135i, 07' 335Xi,
08' STi, 04' 350Z, 04' STi, 02' WRX. 96' GSR, 04' SE-R/SpecV