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Downpipe Install

The stock Evo 8 stock exhaust piping isn't too shabby at with an ID about 2.25", but that's not as good as 3". In an effort to further reduce exhaust back pressure, we will be installing an RMR downpipe to match the RMR catback. While a 3" downpipe can be installed prior to a cat-back exhaust system, it should really be installed after or at the same time. Restrictions should be removed from the outermost point and then work your way in. There is no point in freeing up exhaust flow close to the engine if the exhaust down the line doesn't allow any more air to flow out :)

1. Begin by raising the front of the car and supporting it on jack stands. Don't forget to chock the rear wheels so things don't go bad. If you have the splashguard still on your Evo, you will need to remove it to access the downpipe/O2 sensor housing connection.
2. With the car safely supported and the splash guard off, you will need to remove the two lower control arm braces. The front bar has three 14mm bolts and the rear has two 14mm bolts.
3. Remove the two 17mm bolts holding the downpipe to the front of the catalytic converter, but leave the hangers connected for now to support the rear of the downpipe while you work on the front connection.
4. Now move to the front of the downpipe where it connects to the turbo (actually the O2 sensor housing) and remove the two 14mm spring bolts. With the front of the downpipe disconnected, return to the back and remove the two 12mm bolts holding the downpipe to the hangers and remove the downpipe. TECH TIP: Pull the downpipe straight down off of the O2 housing. Moving it around too much may damage the donut-style gasket between the connection.
5. With the stock downpipe out of the car, compare it to the RMR downpipe and you'll get a good indication of how much more freely the exhaust will flow!
6. Clean off the recessed section of the oil pan where the downpipe runs under it and attach the self-sticking ThermoTec heat shield included with your RMR downpipe. The ThermoTec may need to be trimmed a few inches for a cleaner fit. Sorry, forgot to take a pic of it until after the downpipe was already installed, but you get the idea :)
7. Naturally, installing the RMR downpipe is the opposite of removing the stock one and uses all of the factory bolts and gaskets. Begin the installation by first hanging the downpipe on the hangers at the rear.
8. Raise the front of the downpipe over the donut gasket at the O2 sensor housing and reinstall the factory spring bolts.
9. NOTE: The RMR downpipe, as well as most aftermarket 3" downpipes, does not fit with the lower control arm braces installed. The rear bar on our Evo managed to fit with minimal clearance, so we left it on, but don't count on keeping either one. If you would like a replacement lower brace that fits with 3" downpipes, check out the RMR brace in the Suspension section of our online catalog. Back at the rear of the downpipe, make sure to replace the factory gasket between the converter and downpipe and then reinstall the factory bolts holding the two together. Your new downpipe is installed!
10. As with all exhaust components, start the car and check for any leaks before you take it out for a test drive and then enjoy it!

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