Project Lexus IS-F Part 2: We test the PTS – Joe Z Series Exhaust

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Well the good news is that our car had the same power as before, 22-25 more hp.  Our theory to why some people have had puzzling results is that we learned that an IS-F can have a lot of variability on the dyno as it warms up.  The power can vary by more than 20 whp until it reaches operating temperature for both the engine and drivetrain and settles down.  Dyno operators in a hurry might not ever get the car to the settling point.  Also if the dyno operator tries to cool the car down by turning it off between runs to get a really good run, there is a lot of variance.  The car should be left running while the dyno fans drop the coolant temps to normal operating range for consistent readings.

Perforated core resonators are low restriction.  Perforated core mufflers have the lowest possible restriction.

 The second question brought up on the forums was would the intake make good power if the car was dynoed in sixth gear.  We had originally wanted to duplicate K&N’s test which used third gear.  We repeated the test using sixth gear which is closer to a 1:1 ratio.  The power numbers that the K&N Intake produced were once again about identical for peak output of 22-25 more hp, but the power curve was slightly less smooth.  We feel that this demonstrates that the K&N intake not only works well but has repeatable power.  All future testing of parts on the car, we will use sixth gear.

The main mufflers show the straight through perforated core low restriction design of the mufflers.  Perforated core mufflers are known as absorption type mufflers and have the lowest backpressure.

So on to our PTS - Joe Z exhaust testing.  Looking at the stock system, we felt that there was plenty of power to be gained.  The tubing was subjected to some tight bends and severe neck downs in some areas.  The mufflers were reverse flow designed to be really quiet.  To us there was a lot laying on the table here.

PTS or Performance Tube Systems makes the exhaust to Joe Z’s specifications.

The Joe Z exhaust is made for Joe Z by Performance Tube Systems or PTS, a quality exhaust fabricator that makes high quality aftermarket exhausts as an OEM for several different companies. When examining the Joe Z exhaust we were pretty impressed.  The entire exhaust is made of 304 alloy stainless.  Your typical stainless exhaust is usually made of cheaper grades such as 409 or 419 with only the tip and muffler can being 304 since 304 polishes better.  These lesser grades of stainless are not as corrosion resistant and turn a purplish brown color and can actually corrode through after a while.  304 is much more resistant to corrosion, especially at higher temperatures.

The PTS – Joe Z exhaust comes with all gaskets and good quality hardware.  We applied antiseize on the bolts to ensure easy disassembly should we have to in the future.