Tech: Exhaust Header Install on Lexus IS300


Exhaust headers are crucial for power gains and more so contribute to the signature exhaust note from engines, especially on the naturally aspirated 2JZ-GE on this Lexus IS300. The owner needed to replace the factory piece that was starting to show severe signs of wear through the endless heat cycles and in the meantime, could also get a nice shiny new piece under the hood – a true win-win. For the replacement, the owner chose a piece from Megan Racing as it was a perfect bang-for-the-buck compared to an OE unit. For those looking to do this install, it is advised that you take your time as the cramped room in the engine bay will prove to be quite frustrating for the average gear head.

Step 1: Disassemble plastic (Lexus) engine cover
– Using a 10mm socket, remove the nuts holding the engine cover to the engine.

Step 2: Unplug Mass Air Flow (MAF) sensor & Intake system
– Remove of the MAF is fairly simple as it uses a clip-system to secure it to the plastic intake pipe. Pinch the clips and loosen accordingly.
– Use a 10mm socket to loosen the clamps securing the plastic intake pipe from the air box and into the intake manifold / throttle body.

Step 3: Unplug O2 sensors
– There are three (3) O2 sensors that need to be unplugged, again using a clip style system. Be careful when removing them as the plastic might be brittle.

Step 4: Disconnecting exhaust piping from header
– With the vehicle elevated, remove the two nuts that secure the factory exhaust piping to the lower part of the header system. Make sure the vehicle has been sitting for some time as the exhaust piping can still be very hot.

Step 5A: Removing the exhaust header
– Using a 14mm socket, remove the nuts securing the exhaust manifold to the engine.

Step 5B: Removing the exhaust header
– Using some strength, wiggle the exhaust header from the studs. Due to normal wear / tear, the header might be stubborn to come loose. Make sure not to damage any of the studs from the engine during the process.

Step 6A: Removing existing exhaust gasket
– Using one’s fingers, remove the existing exhaust gasket.

Step 6B: Prepare exhaust ports and install new gasket
– Using an Emery cloth, smooth the exhaust ports where rust and debris have built up over time.
– The finish does not have to be perfect, but it is essential that it be cleaned for a proper seal.
– Install new exhaust gasket onto the studs.

Step 7: Install new exhaust header
– With the new exhaust gasket in place, slip on the new exhaust header – some wiggling might be required.
– Tighten bolts on the exhaust header until secure. Make sure to inspect each point for proper fitment.

Step 8: Re-install all factory pieces
– With the new header now installed, begin by replacing the MAF sensor, intake piping and engine cover.
– Go over each fastener and check that all points are secure.

With the Megan Racing exhaust header installed on the Lexus IS300, the test drive is the only final piece to the puzzle… and the fun part too! For the cost of a few hundred dollars and an hour’s time of labour with limited tools, replacing one’s exhaust header is one of the easiest modifications to do on any vehicle. The sound and looks outweigh the cost compared to an OEM piece, the question then remains as always – what’s next? That is up to you.

Words & Photos: Giancarlo Pawelec

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