I agree with green91.

But in your case, your turbo is not really tune to full spool at about 4 to 5k rpm. This is just what happen what a bigger turbo is meeting a smaller engine. Remember, turbo runs off of exhaust gas, which the amount is limited by the motor's displacement.

Get back to the topic. Bigger engine. Drop in B18C and you should feel better, in terms of both increase of power and lag.