Project EVO MR – Engine Bolt Ons Part 2

Project EVO MR – Engine Bolt Ons Part 2

By Cheston Chiu

In the last edition of Project EVO MR, we were at Cobb Tuning SoCal in the middle of bolting on a bunch of parts.  As you may recall, we are wanting to give our EVO a nice boost but don’t want to get too much beyond the basic bolt ons because we don’t want to stress our SST transmission too much.  We want to be able to daily drive our car with occasional track use without problems.

So far we are working on getting the AEM intake, ARC intercooler, Cosworth intake pipes, AMS downpipe, MXP exhaust and the Cobb boost control solenoid with Access port all fired up before some tuning to make it all work.  How much power are we gonna make?  Let’s take a look and see.

With the downpipe and O2 housing removed, the OEM turbo is now exposed.  Since we don’t want to make horsepower more than the low mid 300 whp range the stock turbo will do just fine.  You can see how the stock turbo has a flange that separates the wastegate discharge from the turbine discharge.  This typically helps with spool and gives a little more power than having the flows mix right away.


Check out this comparison between the AMS Widemouth downpipe and factory pieces.  Although it’s not super obvious in the picture, the AMS part has an entrance nearly twice as large as stock with a much straighter flow path into the downpipe.  The part probably flows twice the volume as stock.  A flex pipe keeps stress from the engine rocking on its mounts from breaking the pipe.


The AMS widemouth comes with an extra bung for another O2 sensor in case you wanted to run an AFR meter or put your A/F sensor high in the system for tuning.  The O2 sensor housing part of the downpipe is investment cast stainless which allows for more freedom in design than if it was fabricated from pipe section.  This allows for the best possible flow path from the turbo discharge.  The part has nice thick flanges which ensure a long leak free life.


In our case, Danny just used the AMS supplied plug to block off the extra sensor port..


The AMS downpipe installed.  It’s a big, huge and straight shot to the MXP exhaust.  As you can see, the extra O2 sensor port is in a good place for access while tuning.


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