The actual "reliability" mods for the FD are as follows: aluminum air separator tank, new radiator, all new suspension bushings, new engine mounts, boost gauge, electronic boost controller, Miata thermoswitch, new fuel filter (it's usually neglected), and downpipe.

The boost controller is a bit either/or but as soon as you add a mod or two it's a good idea.

The downpipe is considered a "reliability" mod even though it increases performance because the stock downpipe has a pre-cat which due to the high heat it is subjected to tends to barf up its packing which then travels to the main cat and clogs it up which almost totally chokes off the exhaust.

A Y-pipe, intake, high flow cat, ECU and intercooler are all performance mods.

People are too worried about the ECU when mods are done when really an electronic boost controller will keep everything within control of the stock one.