There are a few to choose from , though for reference Dream were not impressed with the quality of the js racing item they have fitted to their fk8.
A few choices from America , some jdm ones - g-reddy , hks , fujitsubo. The fujitsubo being pretty pricey due to it being a full ti system.
Remus is a safe bet but pricey all things considered.
Milltek should be considered , but they come in about 6000 bits and are prone to knocking and may require adjusting once it has been fitted , these are popular though , every man and his dog has one on the fk2. Dare to be different
Edit to add ; I had both the road plus catback and the race version on the fk2 and although the race version sounded good - In hindsight it got a bit tiresome on the motorway. If going milltek I would go for the part resonated one (road plus)
Regarding intake. Eventuri is out imminently and Dream will take an order. The k&n panel is a safe bet if you want a bit of extra poke (negligible) injen was proven to be problematic on the fk2.
Eventuri would be my choice if I wasn’t too concerned with warranty woes... and if I could justify ~ £1k on an intake.