if extra performance is the goal rather than just noise, there are mods which the ecu doesn't cancel out such as plenum spacer, final drive, flywheel etc. apart from plenum spacer, they won't necessarily give more power but will give more speed.
it does annoy me tho that cars like the skyline just needs a few mods and it gets over 400bhp, and without going f/i you're lucky to get over 300bhp in a z