DR Series 3.5"
Turbo to Tip Race Exhaust
 

   

"the fastest car ever recorded by our Correvit, pulled 1g in acceleration off the line, quicker than a $300K F355 Ferrari!"  

Motor Magazine  

 

 
 
 

Take No Prisoners!

APS DR Series 3.5" Turbo to Tip Race Exhaust
The worlds first bolt-on 3.5" Stainless Steel (304) turbo to tip race exhaust designed for 600+ horsepower. Minimal exhaust back pressure, fast turbocharger spool-up and maximum horsepower is guaranteed.

The APS DR Series 3.5" Turbo to Tip Race Exhaust is a true 3.5" internal diameter exhaust system through each and every section. By utilizing the latest technology precision mandrel bends with the smallest possible bend angles spread over the maximum possible length, optimum exhaust gas flow minimum exhaust back pressure is achieved.

By dissipating the hot exhaust gasses more efficiently, the APS DR Series race exhaust lowers the thermal load on vital engine components such as pistons, combustion chambers, valves etc., particularly at high horsepower levels. Another significant benefit of the DR Series race exhaust is better transfer of exhaust gas energy to the turbocharger which results in faster turbocharger spool-up and more efficient turbocharger operation at high power levels.

A great deal of development effort has also been put into accentuating the deep Subaru boxer engine note - this exhaust is not for the faint hearted and guaranteed to excite!

The comprehensive APS DR Series 3.5" Turbo to Tip Race Exhaust system includes the innovative APS High Flow Turbine Outlet manufactured from Ni Resist iron, 3.5" internal diameter 304 grade down pipe, 304 grade 3.5" internal diameter intermediate pipe with true 3.5" internal diameter resonator, Highly polished 304 grade 3.5" muffler and tip assembly, all mounting hardware, gaskets, stud, nuts etc. for easy installation.

Part No APSWRX-HOE/R5 Suites:

All US Specification WRX and STI vehicles

Australian Specification 1997 - 2005 model WRX and STI vehicles

NOTE: Installation of this exhaust system may affect exhaust emissions. Consequently, APS recommends this system be installed in vehicles intended for off-road or competition use only.

Click Here for information on how Dyno-Comp relies on this precision crafted APS product to build what is arguably the ultimate Subaru high-performance sports car.

Selecting your APS Exhaust System

"How much horsepower will that exhaust system add?"

This is an often asked question, to which there is no real answer. An exhaust system is only a point of possible restriction, which needs to be reduced as required.

For example, in a best case scenario, total removal of the complete turbo back exhaust system from a stock MY01 225 hp WRX will result in a power increase of approximately 20 hp. On the other hand, on a 425 flywheel hp WRX, utilization of the correct exhaust system would literally represent 65 of the 200 hp increase over standard.

A good starting point for the correct choice of an exhaust system, the following should be used as a useful giude:

  1. Street Use - Legal Emissions/Noise - Less than 4.0 psi back pressure
  2. Street Use - No Legaility Issues - Less than 2.5 psi back pressure
  3. Race Use - As low as possible, however no more than 1.0 psi back pressure

The following chart provides exhaust back pressure data for a given engine power level for the stock WRX exhaust system as well as the range of APS High Output exhaust systems. In addition, the chart provides exhaust noise test results as per the SAE J1169 noise test.

Selection of the correct WRX or STI exhaust systems is the appropriate combination of back pressure, catalytic convertor and noise to suit the engine's power output. The bottom line is, if this data cannot be provided by an exhaust manufacturer, look elsewhere.

Exhaust System
Back Pressure (psi) at Nominated Engine Horsepower Level
Noise as tested
to J1169
225hp
325hp
425hp
525hp
625hp
725hp
Stock
with Cat
12.0
-
-
-
-
-
86 dB
Stock
without Cat
-
-
-
-
-
-
-
APSWRX-HOE/R2
with Cat
2.0
3.5
6.0
12.0
-
-
88 dB
APSWRX-HOE/R2
without Cat
0.5
1.5
3.0
4.5
-
-
90 dB
APSWRX-HOE/R1
with Cat
2.0
3.5
6.0
12.0
-
-
93 dB
APSWRX-HOE/R1
without Cat
0.5
1.0
1.5
2.5
3.5
5.0
95 dB
APSWRX-HOE/R8
with Cat
2.0
3.5
6.0
12.0
-
-
93 dB
APSWRX-HOE/R8
without Cat
0.5
1.0
1.5
2.5
3.5
5.0
95 dB
APSWRX-HOE/R5
with Cat
-
-
1.0
1.5
2.0
2.5
98 dB
APSWRX-HOE/R5
without Cat
-
-
-
0.5
0.75
1.0
100 dB

Click Here for video action of the US Spec APS STI fitted with APS High Energy Headers and APS 3.5" Race Exhaust

Hint: Save to disk before playing video

Exhaust Noise Testing
Many statutory bodies around the world currently mandate that vehicles comply with stationary exhaust noise tests specifications - Generally based upon the "SAE J1169 Measurement of Light Vehicle Exhaust Sound Level under Stationary Conditions"

For example, California and various other states in the US mandate J1169 SAE stationary noise tests. In Australia the test requirements are ADR 28/01 stationary noise test and it too is based upon SAE J1169. In fact, the above tests have identical test procedures and only the required limit varies:

USA 95 dB
Australia 90 dB

The test involves positioning a type 1, SIA compliant ANSI S1.4 - 1983 noise level meter, specifically as illustrated in the diagram below. No other positioning is relevant! Noise tests are extremely specific in their scope and must be conducted very carefully!


Diagram from SAEJ1169 Testing Procedures

Engine RPM must be held steady at 75% of rated peak horsepower RPM.

Given the latter figure is 6,000 RPM for the US spec. WRX/STI, the test speed is 4,500 RPM for these vehicles.

International specification vehicles (including Australian) vary as follows:

Vehicle
Rated HP @ RPM
Test RPM
97/00 WRX
5,600 RPM
4,200 RPM
99/00 STI
6,500 RPM
4,875 RPM
01/03 WRX
5,600 RPM
4,200 RPM
01/03 STI
6,000 RPM
4,500 RPM

Again, it must be emphasised, all facets of a noise test must be specifically followed for the test to have any meaning.