Ok....just thinking back to when I did my P20 upgrade, I was thinking of porting the entry to the P20 but found that the my stock up-pipe diameter was smaller than the P20's entry. From memory the stock up pipe was 45mm internal diameter while the P20's entry was 54mm so basically as you can see there was nothing really to port....this is on an 06 XT so maybe the STi's up pipe is bigger. What was your up pipe internal diameter, standard?

Also have you investigated the effects/negative-effects of the way you have ported the inside of your P20?....I have seen it done before but all the way round the casting rather than only one side....I can understand why you did it as per your photo but I'm wondering whether you'll get any strange things going on as the exiting exhaust gases will be more resticted on one side of the turbine wheel than the other.

I also ported the wastegate hole and opend up the size a little too, to prevent any boost creep at high boost.