edit links dont work but here is a copy of hte page



The 1986-92 13B 6-port engines, in stock form with the factory fuel injection, produces similar power gains with either our Header/Presilencer combo or our Cat Replacement Pipe (Downpipe) /Presilencer combination. If you have no intentions of installing our Holley intake System (or any other aftermarket carb setup), we recommend the use of the Cat Replacement Pipe (Downpipe) /Presilencer combo since it offers a slightly quieter exhaust note, is easier to install and is less costly. If you are intending to upgrade the intake or fuel injection system, the Header/Presilencer combo offers the greatest performance potential.

Cat Replacement Pipe (Downpipe)

Will the Racing Beat Cat Replacement Pipe (Downpipe) replace only the cat converters?
The cat replacement pipe connects to the factory exhaust manifold, and the presilencer connects to the factory Y-pipe, replacing all catalytic converters and intermediate tubing. It is not possible to use just the Racing Beat downpipe to replace only the catalytic converters. The use of the Racing Beat presilencer is required to complete the connection to the y-pipe. Although a short length of tubing can be substituted in place of the presilencer, we so not offer (or suggest) this due the unacceptable increase in exhaust noise.

Which Cat Replacement Pipe/ Presilencer combo do I need?
Racing Beat offers a variety of components for the 1986-92 RX-7s that are intended for a specific application. The 1986-88 RX-7 (non-turbo) utilizes exhaust back pressure to operate the 6-Port actuators on the intake manifold. Selected Racing Beat presilencer units include a pickup tube that will provide the correct pressure to operate the actuator valves.