[dremd]

If you think it will help, (I don't know) use a flap sander and a drill inside your intake, I've done a few intakes that way, none turned out as well as the 504 we had extrude honed for a Boat, but for about $40 (probably much less) in flap sanders, and a few hours you have a result similar to Extrude Hone.

My procedure goes something like

2.5" 40 grit everyplace it will fit, do the big spaces first, because the wheel will wear down and end up smaller.
1" 40 Grit everyplace else, again do the larger spaces first, the wheel will shrink with use

2.5" 120 grit to smooth it out
1" 120 to smooth it out

If you want to go all out grab a sheet of 300 grit and wet sand everyplace you can get at in a direction along with the airflow, not really necessary, the 120 leaves a very nice/ smooth finnish in Aluminum.

Drill works well for 2.5" Drill press is best, a die grinder works extremely well with the 1"