you also need to remove and disassemble the head before you port it, then clean it out thoroughly or have it hot tanked and re-assemble. -j
i remember a story about a guy with a 1.8t a4 that did a home made port polish on his car. (got the idea from a honda friend)...long story short he removed the air filter and poared sand down his air box. complained later about having to rev the *** out of it to keep it running