Abstract: A method and kit for determining the effectiveness of an exhaust filter. The method may involve exposing an indicator to an exhaust stream of a engine downstream of the exhaust filter, visually comparing the indicator against test samples, and assigning a level of exhaust filter effectiveness based on the comparison. The method may also involve restricting the exhaust stream, diverting a test stream of exhaust from the exhaust stream, and exposing the indicator to the test stream. The kit may include a collector having a housing defining a flow passage configured to transmit a test stream of exhaust from a engine and a restrictor having a orifice plate configured to restrict an exhaust stream from which the test stream is diverted.