I am interested, what tools do you need to work the material? i was planning on cutting out the ruff shape and using sanding disks to get to the final shape? it's a cheap mod, I don't see how adding 20-30cfm of air flow to the blower case can hurt, and if it does its just as easy as taking it out.

 

I used a dremel scroll saw to cut it out, slightly smaller then the gasket. Then I used (still have to) use a dremel tool with a flap wheel to smooth it out. Took a while to cut out and was a major pain in the ***.

I'm sure a band saw with a metal blade with cut through ½" aluminum much easier then a scroll saw. But it worked.

You will also need to make extensions for the front of the plenum, and get material to make another gasket, unless you decide to permanently attach the spacer to either the blower or plenum.

 

I built one out of 1/2" phenolic. I didn't gain any boost or see any difference. But it sure is a great place to put a nitrous nozzle!!!!
Later
Darrell