XDP is a MBRP Factory Authorized Online Retailer ID# 600207727. We would like you to shop with confidence knowing your purchase is covered by the manufactures warranty. Now you can hook-up to your MBRP 4" and 5" hardware no matter what size your system. Application Guide Part # 4" ID. to 5" OD (Aluminized) UA2001 3 1/2" ID. to 5" OD (Aluminized) UA2003 4" ID. to 5" ID (Aluminized) UA2004 3 1/2" OD. to 5" ID (Aluminized) UA2005 3 1/2" ID. to 4" OD (Aluminized) UA2007 3 1/2" ID. to 4" OD (Stainless) UA1007 4" ID. to 5" OD (Stainless) UA9001 5" OD to 3-1/2" ID (Stainless) UA9003 4" ID to 5" ID (Stainless) UA9004 3-1/2" ID to 5" ID (Stainless) UA9005