Made of austenitic stainless steel, these set feature a newly developed layout with two central link pipes replacing the single stock pipe.Please be aware that part numbers for evolution systems MTP-BM/SS/3H (for M140i) or MTP-BM/SS/4H (for M240i) have to be ordered together with E-BM/SS/3. Both systems are splitted in 2 codes only because of packaging issues.