My 88 had the intake routed into the trunk. I used a 3" tube and it mounted perfectly into the steel tube that runs through the rear firewall in the engine bay.
Sounds throaty now and i like it.
I have the old air box and plastic tubing put away until winter. I like to replace the stock one when it gets very cold.
Also i wish my paint on the exterior was as shiny as the underside of my frunk and trunk...