I'm running stock bov at over 250rwkw.
Exhuast is first. 3 inch turbo back. Try to get a split dump/front pipe. Make sure you get a decent cat.
Panel filter in the stock air box is next. I still have the stock airbox. Nismo, apexi, pipercross and others make good replacement panel filters. kudos motorsports on this forum sell the apexi ones cheap enough.