J-tubes 38mm Type 1These J tubes have a larger outer diameter of 38 mm and therefore also a larger inner diameter of 35 mm. This allows the exhaust gases to flow better, which can quickly reduce the engine temperature by 10 in warm climates. Due to the narrowing at the ends, these J tubes fit into a standard exhaust. The J tubes are sold in pairs and are made of ferritic stainless steel (magnetic stainless steel) of grade 0409 4512. This is a magnetic stainless steel