Remove the turbo charger, take off the rear housing and cut off the orignal wastegate flap door. Get an exhaust valve (old supra ones are perfect size) cut off the stem so you just have the ciricle part. Port the wastegate hole as big as you can while still keeping it small enough for the valve to cover it. Then weld the valve onto the flapper. You might want to shave off some metal from the backside plate of the turbo too. The only exhaust system that won't spike will be so small that you would not want it.