DISCLAIMER

As always, follow all safety protocols. Don't undertake this task if you aren't comfortable with it, fully understand it, and are capable of completing it. The information provided may be incomplete or inaccurate. You are ultimately responsible for anything you do. Neither Redpants, LLC or myself is responsible or liable for anything that may occur.

A question I get very often is where to start with modifying an Aston Martin, especially when it comes to increasing power. My answer is usually to install high-flow cats or cat-delete pipes and an engine tune. The exact parts used for this will depend on which year and model the car is, but the concept is the same. This DIY Guide shows me installing 200-cell high-flow cats on my red 2007 V8 Vantage, but the process is the same for other years and models using high-flow cats or cat-delete pipes.

WARNING: Removal or modification of factory emissions controls, like catalysts, is not legal in all areas. It’s your responsibility to check your national, regional, and local laws if you intend to do this with your car.

Needed

High-Flow Cats or Cat Delete Pipes
- 200-Cell High-Flow Cats (Pre-MY10.5 V8 Vantage)
- Cat-Delete Pipes (V8 Vantage)
- Cat-Delete Pipes (V12 cars - DB9/DBS/V12V/etc)
New gaskets and hardware
New cat-to-mid pipe exhaust clamps (optional)
22mm box-end wrench
Two 13mm box-end wrenches
13mm socket
6-9" extension
Wobble joint (optional)
T30 Torx bit (optional)
Ratchet
PB Blaster or other rust-busting agent
Anti-seize compound
About 2 hours

Before You Begin

Make sure the car is completely cooled off!! You're working with exhaust components that get extremely hot and not allowing them to sufficiently cool off can result in serious injury.

Rust-busting agents can take time to work. You may need to do Step 1 and Step 2 an hour or so in advance of the rest of this job to make it easier to get through rusty fasteners.

You may need two 13mm box-end wrenches for this job because the clearances may be too tight to get a ratchet and socket in some places.

Replacing the primary cats of a pre-MY10.5 V8 Vantage with high-flow cats or cat-delete pipes may require an engine tune, otherwise these modifications may result a check-engine light (CEL) and emissions warning.

Step 1

Get the car on jack stands or use a lift.

Step 2

Use PB Blaster or a similar rust-busting product on all the fasteners at the front of the cats and on the clamps at the rear, and on the o2 sensors where they thread into the top of the cats. You may also want to spray the T30 bolts on the mid pipes just to the rear of the cats.

Step 3

Use the 22mm box-end wrench to loosen the o2 sensors. They don’t need to be removed, but it may help to break them loose now.

Note: If you have trouble reaching them, you can save this for Step 8. You don't need to remove them entirely yet, just loosen them so you can spin them free once the catalysts are ready to be removed. I recommend loosening the o2 sensors (if possible) early because the cat being bolted in place can make it easier to apply loosening torque to the o2 sensors in case they’re difficult to loosen.

Step 4

Use the 13mm socket and ratchet (or the 13mm box-end wrench) to loosen the clamps at the rear of the cats. Spread the clamps apart so you can push the clamps off the cats and onto the mid-pipes.

You can see how corroded my exhaust clamps were in the picture above. If yours are this bad and want to replace them as well, I have them in stock at Redpants.

Step 5

Use the 13mm socket, extension, and ratchet and the 13mm box-end wrench to loosen the top-most nut and bolt of one of the cats. To do this, use the socket, extension, and ratchet and approach it from the front of the car. If you have a hard time with the angle, use the optional wobble joint to make it easier to get the right angle. Use the 13mm box-end wrench to hold the rear of the fastener while loosening it with the socket/extension/ratchet. Repeat for the other catalytic converter.

Step 6

Use the two 13mm box-end wrenches to remove the other two fasteners on each catalyst. Some of the fasteners will be a nut on a stud. For these, the stud should stay in place while the nut spins free… and hopefully, that’s what happens.

The picture below shows the nut-and-stud (left side) and nut-and-bolt (right side).

Step 7

Push the mid pipes to the rear of the car to free up enough space between the cats and the mid pipes. This space will allow you to pull the cats to the rear to clear the studs that connect the cats to the exhaust manifolds. If you're having a hard time getting enough space, use the T30 Torx bit and ratchet to remove the four Torx bolts on the mid pipes just to the rear of the cats (pictured below).

Step 8

Pull one of the cats free and remove the o2 sensors from the cat. Set the cat aside and repeat for the other side. Make sure you remove gasket between each of the exhaust manifolds (headers) and cats.

Step 9

The cats (or cat delete pipes) are specific to each side, so make sure you're putting the correct one in each place or they won't line up properly. You can see in the pic below that VelocityAP identifies each side with "LHS" (left-hand side) and "RHS" (right-hand side). Keep in mind, the side is based on the driver's perspective. In the US, we have left-hand drive (LHD) cars because the driver is on the left-hand side of the car while driving the car. The cars in the UK are right-hand drive (RHD). So, the LHS catalyst goes on the driver's side of the car in a US car.

Put anti-seize on the mid-pipe clamp bolts, then attach one of the cats to the mid pipes and secure with the clamp. Repeat for the other cat, then push the mid pipes back toward the front of the car.

Step 10

Put a small amount of anti-seize on the threads of each of the o2 sensors. Be careful to avoid getting the anti-seize on anything but the threads. Spin the o2 sensors counter-clockwise to "pre-wind" the o2 sensors' wires, then install them in the cats. Pre-winding the wires makes sure they're not twisted once you tighten them into the cats. Use the 22mm box-end wrench to tighten down the o2 sensors.

Note: If you have a hard time holding the cat in place while tightening the o2 sensors, you can do this after Step 11 instead, as there will be more space to work with high-flow cats or cat deletes compared to the OEM cats.

Step 11

Apply anti-seize to each of the new bolts. Hold a gasket in place between one of the the manifolds and cats, then put the new bolts through each of the flange holes. Spin a nut onto each just a few twists but without tightening them down. This will align the manifolds and cats, while also holding the gaskets in place. Once everything's set in place, start tightening them down.

Step 12

Put the car back on the ground. Fire it up and check for exhaust leaks. So long as everything's okay, you're done!