All our standard replacement catalytic converters are fitted in conjunction with you existing exhaust system. Our replacement catalyst will replace the old catalyst on your vehicle, and ensure that your vehicles emissions are compliant with UK regulations


MIJ hi-flow sports cats are 100-200 cpsi as apposed to 400-600 cpsi which a standard (OEM) Cat consists of. Standard (OEM) catalytic converters are restrictive in their flow. The typical flow rate of a standard catalytic converter is around 55-65% whereas our hi-flow sports cats have a flow rate of 75-85%, thus reducing back pressure substantially and increasing performance, especially on turbocharged engines. Emission levels are maintained at legal limits by careful selection of the volume of the metallic substrate.

However, they are designed to work specifically in conjunction with other MIJ Performance products and should not be used on their own (with an OEM exhaust system) or with other manufacturers exhaust systems. We do not guarantee full performance potential when fitted with an alternative to our exhaust system.


We offer standard replacement catalytic converters for all vehicles whether it is a single or twin catalyst setup. We also specialise in hi-flow sports cats for the ultimate aftermarket upgrade. All catalysts are manufactured using the highest quality material including high-grade T316 welding.


Our custom built de-cat pipe is built as a direct replacement for the original catalytic converter. It is compatible with either your original exhaust system or one our performance exhaust systems. Our custom built de-cat pipe is manufactured using T304 stainless steel pipework, it comes with a lifetime guarantee and is a worth while addition for the performance enthusiasts.


MIJ Performance custom build any cat-back system to your specific requirements. Our custom built catalytic back (middle & backsection) exhaust systems comprises of high-grade TIG welded pipework, the resonator (middle box) and the rear muffler (back box). All the relevant sections are co-ordinated together to develop a precisely engineered exhaust system to precisely fit your vehicle. For the finishing touch we offer a wide range of tailpipe styles which you can choose from.