Axle-Back Systems

An axle-back system replaces the exhaust from the rear axle backwards: the rear silencer and its tailpipes. It changes how the car sounds and looks, while the catalytic converters, any particulate filter and the front pipework stay in place. The section holds complete axle-back systems, sport rear silencers and racing versions, each made for a particular model.

The rear silencer is the last place where the exhaust note is shaped. A chambered silencer reflects pressure waves so that some frequencies cancel. A straight-through silencer runs the gas along a perforated tube in absorbent packing, which is louder and freer-flowing but can drone at a steady cruise. Most of the restriction usually sits further forward, so an axle-back changes the sound more than the power.

Narrow the choice with the listing details:

• Car and body style: listings give the model, engine, power in kW and body style. Some are listed separately for single-exit and twin-exit versions of the same car.
• Particulate filter: petrol cars built with a particulate filter (GPF) have their own versions, as do some facelift models.
• Road or racing: the title names the racing versions. Check each listing for road approval: a system without it is for competition use where the rules allow, and can affect a road car’s type approval, inspection and insurance.
• Tailpipes: many systems take a choice of set, such as 2× or 4× Ø 102 mm, 4× Ø 100 mm or 4× Ø 84 mm. Finishes include chrome, black chrome, carbon, carbon with a titanium insert, carbon-insert tips, and brushed, scotched or black PVD-coated titanium. Ends are bevelled, sharp-cut bevelled, or rolled and bevelled.
• Built-in tailpipes: some rear silencers include their tailpipes, listed by number and size, such as 1× Ø 90 mm or 2× Ø 80 mm.
• Material: stainless steel or plain steel. Acidic condensate collects in the rear box, the coolest part of the exhaust, and stainless steel resists it far longer.

An axle-back joins the original system at a factory joint or at a cutting point given in the instructions, so measure twice before cutting. Hang it loosely on its rubber mounts, centre the tailpipes in the bumper openings, then tighten the clamp. Renew cracked or stretched hangers, as a sagging box knocks against the body.

Re-check the clamp and the tailpipe position after a few drives, once the joint has settled. A heat tint on titanium tailpipes is normal. Clean chrome, black chrome and carbon finishes with a non-abrasive cleaner, as polishing paste can wear through a coating.