I used a zip disk, aluminum burrs and 1" flapper wheels to modify my turbo plenum.

First of all cut open the back of the plenum so you can port and polish from both sides of the runners. Smooth out the radius to optimize air flow into the engine.



Porting the runners is the key here. The stock runners are only 53% the size of the intake valves - choke!









You can keep the EGR runner if you want. I deleted mine and had the ports welded up on the runners. You can also remove the webbing between the runers as well. There are a lot of different schools of thought on this one. I like a heat shield with a thermal barrier then leave the runners open so as not to trap heat between the shield and the plenum.







Finish as you see fit Mine is powder coated and the intake is port matched for a spacer and 240SX 60mm throttle body.

 

Beautiful, just beautiful. I wish I had a welder so that I could do as much as you did..

 

Never welded a tack in my life. Had a friend do the welding for me. He said for a cast aluminum manifold it was a dream to work with.

 

Very nice work Fricfrac, 1st class all the way !