[steviek]

Well a maxed out e316g needs about 720cc's (stock 450cc) to still be on the save side. You may be hitting fuel cut or you may be hitting an ecu maximum value of 2.1g's of air /a revolution. At this point the car will jerk back it will feel like you hit something almost. The stock 2g ecu has a limiter which is designed to protect the car from overboosting (basically it was installed so that people didn't blow their engines while the car was still under warranty). Its hard to tell which problem is yours. If the engine hits a certain rpm level all the time under the same WOT and it jerks back then you may be hitting the limiter. If the car gets up in the rpm and then begins to shake violently and lose power and acceleration then it is more likely fuel cut.

About the porting. If you have to ask you probably shouldn't do it. It is a painstakingly long process. You need a air compressor with a carbide tip and it takes hours to gasket match and smooth. Not worth it normally for non enthusiast.
What you can do to help fuel cut is put in a walbro 190 fuel pump. It will improve the cars ability to have higher rpms without jeopardizing fuel economy on the lower end and is ok with the stock fuel pressure regulator. They are 90 bucks. If I were you I would put the boost controller on full close and see if you notice any boost reduction. If not your problem is likely just your wastegate not opening soon enough. Either that or maybe your boost controller isn't installed properly. Try hooking your wastegate straight to the factory boost control solenoid located underneath where the Air sensor is. It looks like to little nipples.
Good luck