Hola, So I drive a 2015 wrx with 30k miles and I have a K&N CAI, and a Rev9 Catless 3" downpipe and an aftermarket single exit 3" exhaust with a cobb stage 2+ tune for such mods... I also just went from 17" rims to 18" so i have taken into thought the idea of my speedometer being off and thats why i think its slow... I need to replace an exhaust gasket but thats the only thing that needs to be done to the car. If anyone has tips let me know!?