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ZZP 3800 Downpipe

Exhaust - ZZP 3800 Downpipe
Exhaust - ZZP 3800 Downpipe

The stock downpipe uses 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.

All downpipes are sold with a high flow catalytic converter. 

Our downpipes are made from high quality stainless steel. Even the flanges are stainless, which isn't something any other company offers. 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. When shopping around, ask if the downpipe is 100% stainless, ask if they use stainless and for a close up shot of their welds. Compare them to ZZP's, and it will be apparent why ZZP's downpipes are leaps and bounds ahead of the competition. They are guaranteed leak free and feature high quality welds, laser cut flanges and 16 gauge metal. We have test-fitted our bolt-in pipes on both stock and modified cars with perfect fitment. Our pipes even include the slight factory angle offset on the flange.

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 possible option. It withstands the higher temperatures of boosted applications and provides a flat smooth surface for the exhaust gas to run over. 

Most common downpipe gaskets can be found here, exhaust manifold to downpipe inlet gasket, downpipe to factory catback/2.5" catback gasket.

04+ Grand Prix' (Series III cars) will require a style "B" o2 extension for the rear o2 sensor. 

Please use factory torque specs when installing our downpipes.

This downpipe is not compatible with any aftermarket headers, it is designed to fit the stock OEM rear manifold.

*Shipping charges are based on dimensional weight


This will only fit the 3800 v6 engine, does not fit LS4 V8 cars, if you have an LS4 powered car, you would want our "GXP" downpipe instead.

This fits on all the following cars:

  • 1997-08 Pontiac Grand Prix with 3800 Series II engine-Both Supercharged and Non-Supercharged cars
  • 2000-05 Monte Carlo 3800 3.8L Engine Only
  • 2000-05 Impala 3800 3.8L Engine Only
  • 1997-04 Regal 3800 3.8L Engine Only
  • 1998-99 Intrigue 3800 3.8L Engine Only

Our downpipes come with a high flow catalytic converter that is 48 state legal. Our catalytic converters will not pass California or New York state emissions. Please contact if you have any questions.

We are currently offering $80 in store credit to purchase your stock catalytic converter back from you. If you're interested, take a photo of your stock downpipe and email it to We will provide prepaid shipping labels for domestic (U.S.) shipments.

Exhaust - ZZP 3800 Downpipe
Exhaust - ZZP 3800 Downpipe
Customer Reviews
4.8 Based on 271 Reviews
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William B.
United States United States
3 inch downpipe

The quality is outstanding as expected from Zzp. I've always received excellent products. The 3 inch catted downpipe made a very noticeable gain in performance on my 04 Monte Carlo Intimidator SS. I already have the 1.0 pcm, Auto Lite 104 Iridium spark plugs, Zzp 10.5 plug wires, Zzp 4k high voltage coilpacks, Zzp 180 degree t-stat, Zzp fuel filter and Zzp 4 inch fenderwall cold air intake. My next purchase will be a 3.4 modular pulley set up, then in the fall front and rear power logs. Thank you for the excellent parts and customer service.

ZZPerformance ZZP 3800 Downpipe ReviewZZPerformance ZZP 3800 Downpipe Review
United States United States
Excellent quality.

I haven't started the car and run it because I'm doing a lot of upgrades but it installed easy, fit perfect, and is cavernous inside compared to the stock piece.

ZZPerformance ZZP 3800 Downpipe Review
Terry M.
United States United States
zzp hi-flow downpipe

I like the downpipe and it's construction quality is superb Perfect welds on the price itself, but kinda seemed like my flex section was just a tad bit loose??? I haven't herd any exhuast leaks yet so I guess it's doing its job! Will be short lived anyways because I'm going to be putting headers on soon anyways!

Amber B.
United States United States
Great Product!!!

This is a very high quality downpipe that is easy to install, and really helps the performance of the car. I have one of these on all 3 of my Grand Prix cars. The factory pipe has a flex joint in it that is cheap and wears out. The ZZP downpipe is a huge upgrade from the factory pipe.

John z.
United States United States
So far so good

Got some new parts from zzp and so far they look awsome gonna go install the high volt coils packs and wires/plugs but I think I found my new l67 part supplier down pipe looks great nice welds will deff post again upon install :))

ZZPerformance ZZP 3800 Downpipe Review