I have a 94 Civic Si with a 2000 JDM ITR (B18C) swap with the factory header (2.5" collector + exhaust donut) and I would like to upgrade to a high flow cat or test pipe. Right now i have the original 94 Si cat on it with a custom flange that accepts the enormous collector but it is extremely restrictive. Does anyone know who makes a high flow cat or test pipe for this header? I have looked around on Ebay and a couple other retail sites with no luck. Thanks for any help.