H-Pipes, X-Pipes & Merge Pipes

Want the two banks of a dual exhaust to work together instead of separately? An X-pipe, H-pipe or Y-pipe connects the banks after the exhaust manifold or headers and can change both sound and flow. These parts are for you if you are building a project with headers or a new system.

The difference between X-pipe, H-pipe and Y-pipe

An X-pipe merges the exhaust's two pipes in a crossover so the pressure between the sides can be balanced. An H-pipe connects the pipes with a balance tube and typically gives a deeper sound, while an X-pipe often sounds raspier and higher-pitched. A Y-pipe merges two pipes into one. For some projects there are also Double X-Pipe and X-Pipe Resonator Delete Kit options, where the resonators are removed, which typically gives more sound. The final sound also depends on the mufflers and the rest of the system.

How to choose the right pipe

Sound is only one criterion. Also consider:

• Pipe diameter: Sizes are given e.g. as 3 x 2 3/4 inches for inlet and outlet and must match both the headers and the rest of the exhaust.
• Catalytic converter: Some pipes have built-in catalytic converters, others are made for installation after the cats.
• Fitment: Several pipes are built for specific headers, e.g. Kooks pipes that require Kooks headers.
• Car and model year: The pipes are made for specific models such as Ford Mustang, Chevy Corvette and Ford Raptor.
• Material: Several pipes are made of stainless steel.

Brands in this category include Kooks Headers, Borla, aFe, CORSA Performance and do88.

Installation, inspection and maintenance

Installation typically requires the car to be raised and the existing pipes to be separated at the flanges or cut. Use new gaskets and suitable clamps, and retighten the joints after the first drives, as the heat can cause them to settle. Removing or modifying catalytic converters can affect both fault codes and vehicle inspection. Whether a pipe is road legal depends on the product and the car, so check the approval for the specific part number.

Frequently asked questions

What is the difference in sound between an X-pipe and an H-pipe?

An X-pipe typically gives a higher-pitched and smoother sound, while an H-pipe often gives a deeper rumble. However, the final sound also depends on the mufflers, pipe diameter and engine.

Can I fit an X-pipe with the stock exhaust manifold?

It depends on the product. Some pipes fit the stock connections, while others are made for specific headers, e.g. several Kooks pipes that require Kooks headers. Check the description for the specific part number.

Can I drive on the road with a pipe without a catalytic converter?

If you remove the catalytic converter, the car may have problems with emissions requirements and inspection. If you want to keep it, there are pipes with built-in catalytic converters or for installation after the stock ones. Check the approval for the part number and car.

Why does the exhaust rattle or knock after installation?

This is often because the pipe touches the floor pan, axle or hangers, or because a joint has settled. Check clearances and hangers, and retighten clamps and flanges once the exhaust has been hot.