I just got a 2004 with 5000 miles. It has Akrapovic full system and PC. The owner said he didnt remember doing anything else when he changed the exhaust. Would you guys advise me to do the Flapper Mod? What else should I do in combination with the full system? Thanks

 

flapper mod ? yes

you could also change your stock air filters for BMC race/street filters that allow in more air as long as you remember to clean them every time you change your oil