991/997 Race Header Installation Guide

READ ALL PAPERWORK BEFORE INSTALLATION BEGINS!

Before installing this product be sure the vehicle is operating at normal performance levels. Make sure there are NO Check engine light, fault codes, or other warning lights on. Make sure vehicle has cooled off completely before working on the exhaust as it will be very hot. 

Installation

1) Remove the rear bumper 

2) Remove side heat shields  

3) Remove rear bumper support 

4) Remove factory exhaust, Side mufflers, o2 sensors, exhaust manifolds/cats.  

5a) Remove center muffler if installing full exhaust system 

5b) Leave OEM center muffler installed if using the OEM header connecting pipes. 

6) Make sure the side inlet flanges of the OEM muffler are loose and that the nuts are at least 3 turns  backed out so that the flange is loose and has ZERO preload on the inlet gaskets. 

7) The OEM Center Muffler may need to be loosened and re-positioned up or down to correctly fit the  side connecting pipes. The exhaust tips will need to be adjusted as well. 

8) Install headers, Thread all nuts on to start and so that they are touching the flanges. Starting with the  center flange, tighten the nuts to spec of 18-lb ft. 

9) Install side connecting pipes into the center muffler. The lower 2.5” pipe is VERY tight fit and may  require some high temp lube or anti seize if it does not want to slip in on its own. The flanges must be  fully loose to slip the 2.5” pipe in.  

9b) Once the connecting pipes are slipped into the center muffler, tighten the flange nuts down until  there is slight preload on the gaskets. From here position the muffler to the correct height so that the V  band flanges align correctly with the headers. Install V band clamps and tighten to spec of 10-lb ft  

DO NOT OVER TORQUE THE V BAND NUTS OR DAMAGE TO THE THREADS MAY  OCCOUR!!!!! this is not warrantied if the flange is damaged in this manor.  

10) After muffler and side pipes have been installed and adjusted, be sure to tighten the center muffler  back up and loosen the nuts for the Exhaust tips for easy adjustment later. 

11) Install O2 sensors. The sensor with the gray rubber covering goes in the longer o2 bung defouler.  You will need to loosen the harness for both sensors near the engine mounts to gain more slack. The  front o2 sensor goes in the other normal location.  

12) Install rubber vacuum line if supplied to new exhaust valve vacuum actuator.  

13) It is recommended to zip tie and secure all hoses and sensors and harnesses out of the way after  installation is complete.  

14) We recommend installing high flow air filters at this time to help improve performance with this  exhaust. This is the time to do so as the rear bumper is off and will allow direct access to the air filter  housing cover. We recommend K&N or BMC filters.  

15) Start engine and make sure there are no leaks and all clamps are tight and secure.  16) Reassemble and install heat shields, bumper support and cover.  

***THE REAR O2 SENSOR GOES IN AN EXTENDED BUNG. THIS IS TO HELP KEEP THE  P0420/0430 CODES FROM BEING SET. THIS IS NOT A 100% GUARANTEE AGAINST THE  LIGHT COMING ON. THIS SETUP HELPS KEEP THE LIGHT OFF MOST OF, IF NOT ALL,  

THE TIME. ACTUAL CEL LIGHT BEING TURNED ON WILL VARY ON HOW THE  VEHICLE IS DRIVEN. LOW RPM HIGHER LOAD WILL USUALLY TRIGGER THE  P0420/430 FAULTS AND SET THE CEL FASTER. BEING THAT THIS IS A RACE ONLY  EXHAUST SETUP, THIS IS MADE TO KEEP THE CEL LIGHT OFF WITH FULL  THROTTLE FULL LOAD OPERATION IN THE HIGHER RPMS, HOWEVER 99% OF THE  TIME THE LIGHT IS OFF ALL THE TIME. THERE IS NO WARRANTY OR GUARANTEE  AGAINST THE LIGHT COMING ON EVEN THOUGH IT RARELY DOES. IF THE CEL  LIGHT DOES COME ON, IT IS RECOMMENDED TO READ THE CODES, CHECK THE  VALUES FROM WHEN THE CODES WERE SET, AND THEN CLEAR. RECHECK IF THEY  COME BACK ON.  

******IF RUNNING VEHICLE ON A DYNO, IT IS RECOMMENDED TO DO SEVERAL  PULLS IN A ROW, SUCH AS 3 TO 5 PULLS AT A TIME TO ALLOW THE VEHICLE TO  ADAPT AND ADJUST ENGINE VALUES TO ALLOW MAXIMUM PERFORMANCE TO BE  ATTAINED. THIS WILL ALSO ALLOW THE ENGINE TO SHOW A CONSISTENT GAIN  AND NOT JUST ONE OR TWO RUNS AS THE FIRST 2 ARE USUALLY INCONSISTENT.