Hm. Okay. Spark plugs arent going to give you anything performance wise. If you want performance upgrades, you wont get them cheap. K&N airfilters are great, because you can clean them and reuse them. Other than that, its not doing much for your performance. You will need to actually invest in your vehicle for any real performance gains.
Upgrades: Free Flow Filter (WAI), Front Strut Bar, Clear Headlight Mod ||| Replaced:Clutch (kit), Front Left CV Axle, Front Left Wheel Studs, Front and Rear Motor Mounts, Muffler (Twice), Trunk Release Latch and Trim, Interior Driver Door Latch, Crank Sensor
Fuel Pump, Fuel Filter, Catalytic Converter
Power Steering Belt, Battery (Twice), 12v Accessory plug, Front Right Wheel Bearing. 160,000 Mi. Will need another clutch put in soon (Release Bearing Issues).