Ok with fuel/timing tuning your 8psi will be fine; however, 400 is the limit on a stock ka (and this is tuning with an AEM EMS.) Ivan has blown quite a few motors at the 400 mark testing this, the pistons just dont hold up. as for changing the pistons to forged then the limit of your block becomes around 500 where your stock rods starts to bend and stock head bolts start to throw in the towel. If you are going to pass 400hp ever in your engine's future. have your motor fully built and do a lot of research over at
http://www.phatka-t.com/s13s14.htm the limit of the fully built KA has not been reached so keep your eyes out 700hp is getting closer.-Dave