Don't waste the time with the d-series. NA or Boosted, its like trying to run boost through a restricter plate motor. The d-series heads are so restrictive even Port and Polished and the SOHC was designed for fuel efficiency and cost effectivness not performance. Talk to anyone... Peter who owns the 9sec gold hatch at Import Source Performance or Sammy at Tiger Racing or even anyone on a tight budget and they will tell you that the D-series is a dead end road. The money spent to attain even stock B-series power could buy you a much better motor that you will be much happier with.