Some at with the cost of performance/comfort- smaller lighter/narrower wheels/tires,the smaller lighter brakes,not using the heat/ac/lights/stereo and any other electrical things, auto transmission swap.
Some that benefit performance lowering the car and other aero mods, front spoiler/air damn (extending not much more than 50mm), possibly vented hood (not the hood scoop kind the kind like evos have), belly pan/under tray for the engine bay and possibly the underside of the whole car, antenna removal, wiper removal. Higher fuel pressure/cooler fuel. Free flowing intake and exhaust, lighter flywheel, pulleys, lighter engine internals.