Something needs to be cleared up here.
The 98 SVT has extrude honed secondary ports in the upper intake and the heads. I'm not sure about the lower intake, but I think it doesn't have the extrude hone process.
The 99 and 00 SVT has extrude honed primary and secondary ports in the upper intake and the heads. Again, I'm not sure of the lower intake. Somewhere along the line the lower intake was enlarged, I think part way through the 99 model year.
So the dual honed intake refers to honing the primaries and secondaries while the single honed intake refers to honing only the secondaries. This change was worth 5 HP.
There is or was a link to the extrud hone company in the links section. You can have most anything done by them, but the cost is quite high when done on an individual basis rather than on a production basis.
A well modified engine such as a 3 liter conversion or an engine with much hotter cams would surely benefit from additional honing, but an experiencied porting shop may be able to accomplish much the same benefit with more conventional porting tools.
