McLaren 600LT Spider KAT catalytic converter kit

Upgrading or replacing the catalytic converters on a McLaren 600LT Spider typically involves moving from the restrictive 4-cat factory setup to a high-performance 2-cat system. This is a popular modification for the 600LT because it enhances the signature top-exit exhaust flames and “crackles” while significantly reducing backpressure on the turbos.

High-Performance “KAT” Kit Options

For the 600LT, most “kits” are actually Sport Downpipes that house high-flow catalytic converters. The industry standard for McLaren is the 200-cell HJS HD core, which provides near-straight-pipe flow while scrubbing enough emissions to prevent a Check Engine Light (CEL).

• Fabspeed Sport Catalytic Converters: These replace all four factory cats with two ultra-high-flow HJS German 200-cell units. They include military-spec thermal blankets rated to $2,200^\circ\text{F}$ ($1,200^\circ\text{C}$), which is critical for protecting the 600LT’s rear deck components from the extreme heat of the top-exit exhaust.

   

  • Performance Gains: ~30 hp and 33 lb-ft of torque.

     

  • Fitment: Guaranteed no CEL and fits both Coupe and Spider models.

• Novitec Sport Metal Catalysts: Part of the Novitec performance program, these are often sold as a set (Article No. C1 600 60). They are designed to integrate seamlessly with the Novitec Tectronic (to prevent CEL) and their power-optimized exhaust systems.

• Fi Exhaust Sport 200-Cell Downpipes: Frequency Intelligent (Fi) offers high-performance downpipes (Part MC-MP4-CAT200) that prioritize a high-pitched “Formula 1” sound profile.

OEM “Re-Coring” Service

If you want to keep the factory look for inspections or warranty purposes, companies like Fabspeed offer a Re-Coring Service.

• How it works: You ship your OEM catalytic converter housings to them, and they replace the restrictive ceramic factory internals with high-performance HJS tri-metallic cores.

   

• Benefit: From the outside, the part remains 100% original, but it flows and sounds like a race-grade system.

Technical Summary & Comparison

Important Note for Spider Owners

The 600LT Spider’s top-exit exhaust is positioned directly under the rear tonneau. When installing an aftermarket “KAT” kit, thermal management is non-negotiable. Ensure your kit includes high-quality heat blankets (Inconel or specialized basalt fabric) to prevent the heat from melting your paint or damaging the roof’s hydraulic lines.