if the 02 housing with external dump for the waste gate(screamer pipe) is for a rwd sr20det it would be setup for the skinny 02 sensor. The usdm is sensor is a different size. You may need to have the correct size welded bung on. Also make sure if you removed the 02 sensor off your car to check that the bung did not come off with the 02 sensor. This happens and would make the usdm sensor not fit if the correct bug is welded on the 02 housing you bought.