Porsche 996 Turbo NHP Exhaust with Sound Valves
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The NHP Exhaust System with Sound Valves is offered as a Turbo Back System or you can purchase this exhaust with our 42.7mm Headers or 44.5mm Headers.
For a description of our exhaust headers please click here.
Please read our extended description below.
This exhaust has been designed to almost completely bypass the exhaust mufflers when the valves are open travelling through 2 channels with most of the exhaust gases exiting directly through the exhaust tips and partially through the mufflers 90% will exit directly and 10% of exhaust gases will travel through the mufflers, when the valves are closed 100% of exhaust gases travel through the muffler.
What happens when the valves are open?
You get an aggressive sounding exhaust surprisingly not obnoxiously loud but in my opinion the way a 996 Turbo should sound at all times, obviously cabin drone at acceptable levels is to be expected when valves are open due to most of the exhaust gases that are bypassing the mufflers.
What happens when the valve are closed?
You get a civilized 996 Turbo that sounds very similar to the factory exhaust system just a notch louder.
What's the piping size and what about engine power?
The piping size when bypassing the mufflers is 70mm which is larger than factory piping size of 62.5mm this results to a 10% larger piping which improves exhaust flow. When the valves are closed the exhaust gases will go through a 51mm pipe ,the valves closed setting is recommended when driving normally in the city at lower RPM range (below 5500 RPM) or highway cruising if you have to push the car the open valve position is highly recommended so that the engine can breathe like it should.
With the valves open you enjoy a free flowing exhaust system that unleashes the power of the 996 Turbo, you are basically bypassing the mufflers and that's when this exhaust will make most of its power especially at high RPM's, in addition you get the hear the Turbo's winding which is PRETTY COOOOOL.
There's no doubt in our minds that this exhaust makes good power especially with the valves open. We have done most of the testing on the sister 997 Turbo which is pretty much the same as a 996 Turbo , I personally own a 997 Turbo and I can feel the extra ponies it just pushes like crazy when driven hard.
Are the valves reliable? How do they work and how do you activate them?
We have developed this exhaust in early summer 2012 and have tested this exhaust on our own 997 Turbo ever since, extensive testing has been done prior to releasing this exhaust, rest assure you will be getting a high quality exhaust backed with a lifetime warranty.
The valves are mechanical and work with engine vacuum, you can activate the valves with the included FOB remote or you can hard wire a ON/OFF switch inside the cabin (our preferred method)
Left + Right Mufflers with Valves and 200 cell cats
Exhaust Metal Band Supports
Fob Remote + Module and ON/OFF switch
What about installation?
Installation of the exhaust doesn't require any modifications, you drop the factory exhaust and install the NHP exhaust with valves. The most difficult part is to get a vacuum source, unfortunately on the 996 Turbo one can use more space to work in the engine bay, vacuum line are normally located behind the plenum , you will need to tap into a vacuum line with our included "Tee" vacuum adapter. We recommend installation to be performed by a qualified technician. About the valve control, using the FOB remote is the easiest as you can install the FOB remote module in the engine bay (behind a tail light) this avoids passing any wiring into the cabin but personally I much prefer an ON/OFF switch in cabin which long term proves to be more reliable and you don't have to worry about losing or misplacing a remote, regardless both are included and the choice is yours.
IMPORTANT MESSAGE ABOUT 200 CELLS CATALYTIC CONVERTERS.
For the State of California our Exhaust Products are not C.A.R.B.
Our Exhaust products have no guarantees about passing emissions in your state.
Our High Performance Exhaust with sports catalytic converters are built and meant for off-road purposes.
Our Exhaust Products “Lifetime Warranty” does not cover catalytic converter error codes.
Please note that when installing High Performance Catalytic Converters there is a possibility that you may get a “Check Engine Light” for Catalytic Converter Inefficiency or other Catalytic Converter related error codes. This may or may not happen, this is due to lowering the Cell Count of the catalytic cartridge, in other words we need to work with the same surface area with a lower cell count, most OEM Catalytic Converters will have 600 to 800 Cells per square inch, High Performance Catalytic Converters are only 200 Cells per square inch. If you get a check engine light it’s not because the product is defective but it’s the ECU picking up the difference and relating those error messages.
There are several ways to deal with this.
Most Efficient is the Flash the ECU with performance software, make sure to tell your tuner that you have 200 Cell Cats. This is the most expensive and most efficient.
Use 02 Bungs, many have been successful by using 02 Bungs however this is not 100% Bullet Proof.
Purchase OBD2 Scanner, read your codes and erase them. For those of you who are not annoyed by the use of a scanner on a weekly basis this is the cheapest solution.