I know this is old, but heres my take.
I have been working on a rb20det head. From what I have been told, unless you know 100% what your doing DONT MESS WITH THE SHORT SIDE. You can really mess up the port and lose a ton of power by over porting or miss shaping that. Air goes in a straight line, and really does not like to turn. With that, you can see good gains by removing stuff around the seat, NOT much but some. Also DONT OPEN THE PORT ANY unless your looking for big big top end power. The first little bit of the port is what gives the speed, the rest tells how much air can flow at that speed. Now if you port one part you have to open the rest. If your port flows 200cfm at the port open, 150cfm in the middle, 125cfm athe the throught, and 100cfm at the valve seat. Now you ported the opening a little and made it flow 230cfm, you still will only see 150cfm, 125cfm, and 100cfm at the valve seats. If your going to port any where on your head, at least clean up the whole port. Be carefull not to take out too much stuff, and be carefull around the short side turn.
What I did to my head was shrink the splitter in the intake port, opened the throught (I didnt mess with the short side much at all) a little, and got a 3 angle valve job. This should improve flow throught the whole port and not slow the air down. Now time for the before and after pics....
Before
After. I didnt mess with the outside walls only the inside splitter.
This is my ex port where I removed the stud hump