Phase 1: Top-Side Preparation

1. Power Down: Disconnect the battery in the trunk. This is critical as you will be working directly next to the starter motor.
2. Clearance: Remove the plastic engine cover and the air intake assembly.
3. Reservoirs: Unbolt the coolant expansion tank (10mm) and the power steering reservoir. Do not disconnect the hoses; simply tie them back toward the strut tower using bungee cords to clear the workspace.
4. The Steering Shaft: Mark the steering shaft and the rack input with a paint pen to ensure perfect alignment upon reassembly. Remove the 10mm and 12mm pinch bolts and slide the shaft off the rack.

Phase 2: The Under-Car Strategy

1. Raise the Vehicle: You need at least 24 inches of clearance to "fish" long-tube headers up from the bottom. Secure the car on heavy-duty jack stands.
2. Exhaust Removal: Remove the mid-pipes. If you are on an older model (2005-2010), spray the 15mm flange nuts with PB Blaster 24 hours in advance—they are notorious for snapping.
3. The Starter: On the passenger side, remove the two 15mm bolts holding the starter. Disconnect the wiring and set the starter aside. This is the only way to access the rear manifold bolts.
4. Engine Lift (Optional but Recommended): For Long-Tubes, loosen the 18mm motor mount nuts. Use a floor jack with a wood block on the oil pan to lift the engine roughly 1 inch. This provides the "swing room" needed to fit the header flange past the frame rails.

Phase 3: Header Installation & Sealing

Remove the factory manifolds and the thin shim gaskets. Pro Tip: Throw away the paper gaskets that come with most aftermarket headers. Use Multi-Layer Steel (MLS) gaskets for a permanent seal.

• Driver Side: Install the header from the bottom. Start the front-most and rear-most bolts, slide the gasket in, and then install the remaining 6 bolts.
• Passenger Side: Remember to reinstall the oil dipstick tube as you are bolting the header in. Most headers require a 1/2" spacer on the front-top bolt to clear the dipstick bracket.
• O2 Sensors: Install O2 sensor extensions (typically 10-inch extensions are required for the front sensors on long-tubes). Apply a tiny amount of anti-seize to the sensor threads, keeping the tips clean.