I ported the drivers side using the traditional carbide burrs and sandpaper abrasive rolls. This method is effective but takes time to master, creates a huge mess, and poses the risk of gouging the aluminum from bad technique or a moments loss of concentration. That’s when I came across an elegant solution considering the straight tunnel ram style. Use ordinary metal files! They are very precise, carry a low risk of damage, and so clean you can work on the intake on your desk at work!