BM Catalysts BM91248H vs VW 1J0 254 400 HX

This part from BM Catalysts is usable. However there are differences in production quality and I would recommend using a slightly better aftermarket product from another company or genuine VW item. ( 1J0 254 400 HX , 1J0254400HX , 1J0254400 )

First difference is that BM Catalysts part is 2.1kg and genuine VW part weights 2.8kg

Another difference is that the catalytic converter itself is much further away in BM Catalysts product compared to genuine VW product.

This cause the bulged part to sit slightly more back compared to original catalytic converter. Probably this is due to production margins and bolt lengths the BM Catalysts is using. This looks quite ok when installed. But there is more space on the front part of the car. (probably space left specificly for catalyst).

Now the real problem with this product is that the catalytic converter is thinner but longer. BM Catalysts part has radius about 9cm length of 16cm meanwhile the genuine VW part has radius of 13cm and a shorter length. This means that the BM Catalysts product will restrict gas flow more than the genuine VW part.

I guess BM Catalysts save money using one size fits all approach. So same catalytic converter piece is welded to different products.

I would recommend getting the genuine VW item or a catalytic converter which resembles the genuine item more closely.