Retrofit NPP Exhaust onto vehicle not factory equipped

[bisel]

The question has come up a few times and certainly seems like an option where owners have a desire to add NPP exhaust and functionality onto a car not already equipped. One can do this at a relatively low cost, I thought this info might help.

First, you would need to acquire the NPP exhaust silencers. You should be able to find these used for a reasonable price. I don't know what you would have to pay, but I would guess less than a couple hundred $$. At this point, you could just leave it as it is, but the exhaust will remain in the open (or bypassed) position. This might give you exactly the effect you want. But, if you want to be able to control the bypass valves, you will need to get some more stuff.

Luckily, the extra stuff you will need should be relative low cost.

1. Vacuum Accumulator Tank ($25)
2. Vacuum Check Valve ($3)
3. Vacuum Solenoid Valve ($20)
4. Two vacuum T-Connectors ($2)
5. Several feet of good quality vacuum tubing ($15)
6. A remote controller ($78)

The costs shown above are estimates based on sampling of prices on Amazon.com.

Here is a pictorial of the installation. A couple of points I think are important:

• Tap into existing engine vacuum but take care to use a vacuum line that is not for safety purposes such as brake booster
• Critical that you install a vacuum check valve and that it be included as close as possible to the T-Connector used to tap into the existing vacuum line
• You must use a vacuum accumulator tank to maintain vacuum when engine vacuum does not exist such as open throttle position
• Route vacuum lines carefully avoiding high temperature components such as headers, exhaust pipes, etc.

I welcome any feedback. I expect there are others who have done something similar and your experiences would be welcome.

Steve

[FloridaBill]

I have NPP on my car and immediately pulled the fuse. Quite frankly, if my car didn't have it I wouldn't go through all the trouble of retro fitting it. There are simply too many quality systems out there that could be installed with a fraction of the headaches.

Just my opinion.

[forzasteve]

Originally Posted by FloridaBill

I have NPP on my car and immediately pulled the fuse. Quite frankly, if my car didn't have it I wouldn't go through all the trouble of retro fitting it. There are simply too many quality systems out there that could be installed with a fraction of the headaches.

Just my opinion.

I think for most people, your option is one that they would prefer. Certainly, the NPP exhaust when opened up is not so loud to be obnoxious. So for a few hundred $$, you can put the NPP exhaust on the car and just leave the bypass valves open. But, for some people, they find always open to be too loud, e.g., they may have installed other options such as headers, high-flow cats, etc.

Another option to get a bypass exhaust is to get new mufflers that have electrically activated bypass valves. One manufacturer that comes to mind is X-Force. One can get the full cat-back system for less than $1200 or just the mufflers themselves for quite a bit less.

But, if one can get a used NPP exhaust for a bargain price, then it would be hard beat the overall cost going with this compared to purchasing all new components.

Steve

[FloridaBill]

Originally Posted by forzasteve

But, for some people, they find always open to be too loud, e.g., they may have installed other options such as headers, high-flow cats, etc.

Steve

This is true Steve, good point.

[SGRALLEY]

Originally Posted by forzasteve

I think for most people, your option is one that they would prefer. Certainly, the NPP exhaust when opened up is not so loud to be obnoxious. So for a few hundred $$, you can put the NPP exhaust on the car and just leave the bypass valves open. But, for some people, they find always open to be too loud, e.g., they may have installed other options such as headers, high-flow cats, etc.

Another option to get a bypass exhaust is to get new mufflers that have electrically activated bypass valves. One manufacturer that comes to mind is X-Force. One can get the full cat-back system for less than $1200 or just the mufflers themselves for quite a bit less.

But, if one can get a used NPP exhaust for a bargain price, then it would be hard beat the overall cost going with this compared to purchasing all new components.

Steve

That's exactly why I chose to use this exhaust and I got it for $200.00.

[cadyshac]

I have NPP on the '11 SS with long tubes, no cats and the valves always open. It's not too loud for me but if it was I would figure out a way to control the valves. I only paid $300 for the complete exhaust system, it is high quality, free flowing, fits perfectly and is in 1 piece unlike the aftermarket systems that have to be shipped (so they come in several sections)

[KaBoom1701]

I did this on my v6....search the LFX forums for the thread...

[forzasteve]

Hi Guys,

Although I would really like to sell you one of the Forza exhaust controllers, I know some people are really the DIY types and would like to be able to manually control the exhaust bypass valves at the lowest possible cost.

If you are one of these types, here is the info you need ...

Get a fuse tap. It also known as “add-a-fuse” or “add-a-circuit”. You can get one these from Amazon, eBay, etc. Also, get a simple on/off switch. There are many types. Choose the one you like.

You will need to add a wire to this fuse tap. Easiest way is to use 18AWG wire and strip the end about 1/4 inch. Tin the wire with solder. Now squeeze the end with a pair of pliers to flatten it a bit. Now you will have a rigid end to the wire. Insert this into the bottom right of the fuse tap. If you prefer, you can can crimp a narrow spade connector on the wire and insert the spade into the bottom right slot.

Now, on your Camaro, go to the fuse block in the rear of the car. It is located behind the right-hand panel inside the luggage compartment. Find the fuse labeled EXH FLAP. Remove the fuse. Insert this fuse into the top position on the fuse tap and you will end up with a modified fuse tap resembling the illustration that is attached below.

Mount the On/Off switch in a location that is easily reached when driving the car. Attach two wires to the switch contacts and route these wires back to the modified fuse tap. Splice these two wires into the fuse tap. Refer to the last illustration below. Insert the modified fuse tap into the EXH FLAP fuse location and now you have two wires coming off of this location going to the switch.

**** Word of Caution **** The fuse location is always hot. Do not insert the fuse tap back in position until you have installed the switch and attached the wiring back to the fuse tap.

You are done. Total cost should be less than $10 to $15.

Using the switch, you will enable or disable operation of the vacuum solenoid valve that controls the bypass valves on the mufflers. When disabled, the bypass valves will be open. When enabled, the bypass valves will be managed by the car’s ECU.

If you want to reverse this to return to pure stock, simply remove the fuse tap, insert the fuse back into the EXH FLAP position. Done.

Best regards,

Steve

[olblue75]

Where's a good place to get the vacuum accumulator tank???

[Jylee]

I follow the instruction from link "functional npp for $50" I use a vacuum switch, two tee, some vacuum hose. No need to install tank or controller. The manual switch turn the vacuum whenever I need the exhaust on or off

[washd0403]

Is anyone selling their npp or zl1 quad exhaust system?

[forzasteve]

You can get a vacuum accumulator tank on amazon.com ...

http://www.amazon.com/Dorman-HELP-47.../dp/B000COB8FA

The link above is not an exact tank for the Camaro, but any tank will do. You could drop by a Chevy dealer and ask for the specific unit for the Camaro. Not sure what it will cost. The vacuum tank is not rocket science, so any will do fine. Some vacuum tanks may have a built-in check valve. This is fine if your install the tank near the engine so have a short run of vacuum line to the vacuum source. But, if you install the tank far away from the vacuum source, then I would get a vacuum check valve to prevent inadvertent leakage that might be caused if you get a break in the line.

You want the tank to accumulate vacuum for use during times that the engine is not producing vacuum ... e.g., wide open throttle. Not a huge deal ... but if you lose vacuum, then the exhaust flaps will open. There may be times you do not want that to happen and a tank will help preserve the closed state of the bypass valves. All cars with dual mode exhaust systems that are vacuum actuated have tanks. Without the vacuum reserve, a simple blip on the throttle will open the bypass valves. You may not want this to happen and the tank will prevent it.

The vacuum solenoid control valve should have two ports for vacuum connection and third port to vent to atmosphere. Your best bet here might be to go the Chevy dealer and get the part for the Camaro with NPP ... but in truth, any solenoid control valve will work as long as it has two ports plus a vent to atmosphere. When the solenoid is activated it provides vacuum from the tank to the flaps. When the solenoid de-activated, it routes air passage from atmosphere to the exhaust flaps. You want to make sure that in the de-activated mode, there is free flow from the atmosphere vent port to the port to the flappers and restricted flow from the tank port to the flapper port. In activated mode, free flow from tank to flappers and restricted flow from atmosphere. Some solenoid valves may not provide a vent to atmosphere. Make sure the one you choose does.

Regards,

Steve

[Z28COP]

I added a factory NPP. welded it on at the cross pipe. Sounds awesome and always open. No reason to waste more $$$.

[JD555]

Steve I tried to purchase but am getting a message there is a problem with your site. Any ideas?
thanks