Yes, there is power to be gained. I used to port alot of intakes for the BON and corral guys, and while it's not necessarily a "port" job, it was worth 10-15rwhp. I personally gained 17, but it was probably a fluke. The most power is gained above 6k, especially at redline. You can expect to gain about 2 mph @the track.
The 6 inch runner intake I made a couple years ago carried the power up really high, but the loss down low killed any practicality for street use.
My 10 inch runner intake is a whole different story. I gained power across the board, over and above the gains made by my ported stock intake. No power loss down low, and I gained about 30rwhp over the ported one, at redline. Check out my 10 inch runner thread.
The 10" runner; is that shortening or lengthening the runners? I have not pulled my intake apart yet, but would like to try it if it isn't too difficult. Do you think this can be done by someone with basic knowledge? I know someone that I can get to do the alum. welding for me.
Thats shortening the runners about 2 inches. The 2 corner ones get shortened about another half inch.
Dont even try it unless you have access to a mill, since it cant be "pulled apart" by any means. It all has to be cut apart and milled.
I really wouldnt try it if you havent ever done any porting work.