Stock downpipes are double-walled tubing with an inside diameter of just over two inches. Following the restrictive downpipe section, the stock unit subjects the exhaust gases to the choking effects of the catalytic converter. After the cat, it flattens out into a section dubbed the infamous "U-Bend," which is a section of pipe crushed into a "U" shape by GM in order to fit a rear O2 sensor. This section has less volume than the same length of 2" pipe, and approaches the volume of a 1.75" pipe with the rear O2 sensor in place! Our downpipe eliminates all of the aforementioned problems! Gains of over 15HP have been seen, along with a substantial drop in knock. Most users can drop a pulley size and/or eliminate 5-7 degrees of knock. This part can typically be installed in under an hour.
Our aluminized downpipes remove the inlet restriction, Ubend (on bolt in models), and include a stainless braided flex section as well as stainless high flow cat. They are guaranteed leak free and feature high quality welds, laser cut flanges and 16 gauge metal. We have test-fitted our weld-in and bolt-in pipes on both stock and modified cars with perfect fitment. Our pipes even include the slight factory angle offset on the flange.
Our 304 downpipes are made from high quality 304 stainless steel. Even the flanges are stainless, which isn't something any other company offers. This ensures a lifetime of rust-free operation and eliminates the need for paint that could flake off. 304 stainless costs a little more but we feel it's worth it. All welds are held to the strictest of quality control standards to ensure a professional finish. Our Weld quality is higher than any other downpipe manufacturer. A sample of one of our welds can be seen here. When shopping around, ask if the downpipe is 100% stainless, ask if they use 304 and ask for a close up shot of their welds. Compare them to ZZP's downpipes, and it will be apparent why ZZP's downpipes are leaps and bounds ahead of the competition.
For a limited time ZZPerformance will be giving out $50 coupon codes for returning your stock downpipe to ZZP for catalytic converter recycling. You don't even have to pay for return shipping! Simply select "prepaid return label" from the drop down and we'll send you a return shipping label with your purchase. Then put your old downpipe (or just the cat) in the package that the new one comes in and drop it off at any UPS shipper(excluding the catback box due to being oversized). We'll email you a coupon code good for $50 off of your next ZZP purchase! Returned units can be cut up but the OEM converter must be intact. Already bought our downpipe? We'll still offer the $50 coupon code but you'll have to pay for the return shipping.
Note: We can only issue prepaid shipping labels to people in the lower 48 states, this excludes our Canada, Hawaii, and Alaska customers.
To take advantage send to:
ZZPerformance
Attn: Core Returns
2575 28th st SW
Wyoming MI 49519
For everyone: Include your original order # and email address to send the coupon code. Write down your return tracking number for your records!
Shorty pipes weld directly to your factory converter. They do not replace the Ubend. They are generally used for custom applications and defective OEM downpipe sections.
Bolt in off-road pipes do not have converters in them. You will need an O2 sim or PCM programming to remove the 137-141 & 420 codes. They are not legal for use on public roads. They provide maximum HP gains and minimum weight. They bolt into a stock or aftermarket cat back exhaust system. They do not include an O2 bung for the secondary O2 sensor unless selected from the drop down. All bolt in downpipes have a 2.5" exit flange that bolts in the factory location, if you would like a 3" exit flange please attach a $20 custom payment to your downpipe order and we will include the correct bolt in flange.
Bolt in with cat downpipes can be used on stock to highly modified cars. They do not require PCM programming and are emissions legal. We use Magnaflow, high flowing catalytic converters. They should not void your factory warranty. They bolt into a stock or aftermarket cat back exhaust system. They include an O2 bung for the rear factory O2 sensor. All bolt in downpipes have a 2.5" exit flange that bolts in the factory location, if you would like a 3" exit flange please attach a $20 custom payment to your downpipe order and we will include the correct bolt in flange.
Weld in with cat systems have a 3 inch exit for use with custom 3 inch exhaust systems. They do not come with an O2 bung unless it is selected via drop down.
2.5 inch downpipes are designed for naturally aspirated applications where no loss in low end torque is desired. They can also be used in supercharge applications when the lowest possible cost is important. They come with interlock flex standard.
Interlock flex, sometimes called turbo flex is the best flex money can buy. Typically, the downpipes in our market use a single wall flex. This is durable but has a ribbed inside design that can disrupt airflow. This type of single wall flex is what people are running when you hear them complain about a whistling or ticking noise coming from their exhaust section. To remedy these issues, you can buy a double braided flex which has braided stainless on the inside, as well as outside, of the flex. The problem is that they fail very easy on supercharged cars. Interlock flex is the 3rd solution and while is costs more, it is the best. It withstands the higher temperatures of boosted applications and provides a flat smooth surface for the exhaust gas to run over. Click here to see interlock flex compared to single wall flex.
304 stainless is the best material out there for exhaust systems. While some companies brag about having stainless downpipes, rarely will they use 304. The problem with the more common 409 stainless used by our competitors is two fold. First it rusts (picture of used 409 and used 304 ). It will never rust all the way through, but it does develop an unpleasant surface rust shown here. Second, it does not have the thermal properties of 304. 304 is an excellent insulator compared to aluminized or 409 stainless. 304 is used in turbo applications because it keeps the energy of the exhaust in the system and increases HP. Similarly, small HP gains can be had in our cars when the exhaust velocity is kept high. Keeping the heat in also has the benefit of improving the operation of the rear O2 sensor. The 304 works so well, that we can place the rear O2 bung in the 3 inch section of the downpipe on our 304 pipes. Trying that on our aluminized or competitor's 409 pipes has produced check engine lights triggering Catalyst system low efficiency. By placing the O2 in the 3" instead of the 2.5" section of the pipe, we increase the HP gains.
Seen in the pictures below, the stock pipe narrows down to a 2" hole before lowering into the cat. This is very restrictive, causes KR, and introduces a loss of HP.
Please use factory torque specs when installing our downpipes.
*Shipping charges are based on dimensional weight
** Offroad pipes require PCM programming or our O2 sim.
***UPS shipping only please
What do our customers think?
Zoom,
Just wanted to let you know that the Down-Pipe was a breeze to install. It was a perfect fit, even the alignment of the flanges was right on the money. Excellent product. I not only can HEAR the difference, but I can FEEL it too. My car was in need of some exhaust work I guess.
Scott DeVinney
***IMPORTANT information concerning High Flow Catalytic converters*******
The downpipes we sell come with a Magnaflow high performance converter. It is OBD2 compliant but it is on the very edge of being so. The PO 420 code is set when the rear bank O2 sensor PCM thinks that the converter is not doing a good enough job. Because the stock cat is so thick and dense, it can still function when the tune is off or it gets old. The Magnaflow isn't like that. An error in tuning, running too rich, having too cold of a Tstat, too cold of plugs, or an old primary O2 sensor can all affect the engine enough to set a code when using the Magnaflow cat. This code DOES NOT affect the way the car runs, it just sets an SES light. To fix it, you'll need that code removed from the PCM, or you can run our O2 emulator(not available for ALL vehicles), or you can clear the code and try to tune the car in better to allow the cat to operate more efficiently. This is a situation in which your cars stock sensor was not designed with your performance goals in mind. Please make your purchase with the understanding that over time, an SES light could be thrown due to the reasons stated above. This is not grounds for a warranty claim, as a repair or replace of the cat/downpipe would not permanently fix the code.
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