Is it worth porting a HDI head

[Poodle]

The port shape on these is very important for swirl, if you port it and don't know exactly what you're doing you will lose that benefit, which will in turn see a loss of economy and efficiency. A friend looked into it once, enquired at a place that builds the HDi engine into tractor pulling beasties, iirc the bloke said he could get 10-12% without affecting swirl, not that much imo.