Trust Cliosport members to completely deviate from the OP's question and start an argument about this , that and the other lol .
To the OP , personally i'm running a Yozzasport exhaust which is supposedly one of the better exhausts in terms of gains if you believe the hype , whether it does or doesn't is debatable . One thing i can say is it's very well made , looks good so i'm happy . If you don't like noise then this exhaust isn't the one for you , it also seems to be one of the louder exhausts .
As for the air filter . I'm currently running the stock airbox with a oem paper filter . I changed it back when the car went for it's cam / aux belt service a couple of weeks ago . I usually run a simota cone filter inside a custom airbox with 2 air feeds . It might all be in my head , but the car doesn't seem quite as lively running the original airbox and filter . I've cleaned and reoiled the Simota and it'll be going back in shortly . I've also used a K+N and Green cone filter in the same custom airbox and they also felt better than the stock filter . But then again , that might be all in my head . But if i'm happy with that setup thats all that matters
Pics of filter and airbox below :
[FONT=&]
[/FONT]