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      03-07-2016, 10:59 PM   #1
Kevinl
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How critical are down pipes?

I am running a JB4 with map 5 30% e85 70% 91 car has a muffler delete but is stock otherwise I plan on ordering a intercooler before summer

I am torn on down pipes I have to get emissions test every two years and the DP fix seems like a pain since it is not recommended to be left installed. I also don't want the car to smell although the mid cats should clean it up enough.
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      03-07-2016, 11:03 PM   #2
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DP Fix takes 10 minutes to install/uninstall. 20 if you have to remove the cowl. You have a JB4 so it installs right in the harness. It's 3 wires you remove and then install the DP Fix inline. It's all pinned so you're not having to splice anything. Smell is fine once it warms up.
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      03-08-2016, 12:23 AM   #3
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The secondary cats do a great job of controlling any smell. It may smell in an enclosed space like a garage, but you'll never smell anything out on the road.
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      03-08-2016, 01:56 AM   #4
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Quote:
Originally Posted by trohde78 View Post
The secondary cats do a great job of controlling any smell. It may smell in an enclosed space like a garage, but you'll never smell anything out on the road.
Exactly this.
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      03-13-2016, 03:09 PM   #5
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I decided to order downpipes and upgraded intercooler

I didnt want to second guess myself so soon the car will be fbo
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      03-13-2016, 03:26 PM   #6
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Quote:
Originally Posted by trohde78 View Post
The secondary cats do a great job of controlling any smell. It may smell in an enclosed space like a garage, but you'll never smell anything out on the road.
+1. Never noticed any smell with catless downpipes. Cut out my secondary cats and the smell was pretty bad, if it didn't sound so damn good I'd regret it
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      03-13-2016, 04:05 PM   #7
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Well if you live in California, you'll fail with downpipes even with the dp fix. I'm due to smog my car, time to find a shady smog station...
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      03-13-2016, 04:28 PM   #8
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Quote:
Originally Posted by shadow191 View Post
DP Fix takes 10 minutes to install/uninstall. 20 if you have to remove the cowl. You have a JB4 so it installs right in the harness. It's 3 wires you remove and then install the DP Fix inline. It's all pinned so you're not having to splice anything. Smell is fine once it warms up.
Couldn't have said it better myself
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      03-14-2016, 11:20 AM   #9
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Quote:
Originally Posted by Kevinl View Post
I am running a JB4 with map 5 30% e85 70% 91 car has a muffler delete but is stock otherwise I plan on ordering a intercooler before summer

I am torn on down pipes I have to get emissions test every two years and the DP fix seems like a pain since it is not recommended to be left installed. I also don't want the car to smell although the mid cats should clean it up enough.
Just buy the VRSF downpipes and smile when you floor it.
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      03-14-2016, 12:19 PM   #10
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love downpipes, definitely a crucial mod and one of my favorites.
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      03-14-2016, 01:20 PM   #11
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I passed CA smog with downpipes, Downpipe Fix, and JB4 on map 0. the only thing I did was flash the ECU back to stock.
In CA they don't use the exhaust sniffer any more on newer cars. They depend on your post cat o2 sensors to do that. If you have a dowpipe fix, the post cat o2 sensors tell the ECU everything is OK, and when the smog tech checks the ECU via OBD it tells him everything is OK.

A lot of people here will tell you that there is very little power gain from doing down-pipes, and it make sense since all down pipes taper to a 2.5 inch anyway.

With that said the car sound better (possibly helps with the placebo effect that you have more power after install)

I would recommend just gutting your OEM down pipes assuming you don't have a sniffer test in a smog check. This way even if you get an watchful tech, it will even pass the visual, and you get 95% of the benefits of the aftermarket downpipes.
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      03-14-2016, 01:40 PM   #12
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Quote:
Originally Posted by dreyo27 View Post
I passed CA smog with downpipes, Downpipe Fix, and JB4 on map 0. the only thing I did was flash the ECU back to stock.
In CA they don't use the exhaust sniffer any more on newer cars. They depend on your post cat o2 sensors to do that. If you have a dowpipe fix, the post cat o2 sensors tell the ECU everything is OK, and when the smog tech checks the ECU via OBD it tells him everything is OK.

A lot of people here will tell you that there is very little power gain from doing down-pipes, and it make sense since all down pipes taper to a 2.5 inch anyway.

With that said the car sound better (possibly helps with the placebo effect that you have more power after install)

I would recommend just gutting your OEM down pipes assuming you don't have a sniffer test in a smog check. This way even if you get an watchful tech, it will even pass the visual, and you get 95% of the benefits of the aftermarket downpipes.
Interesting you say that I am not worried about the 15 hp the down pipes add not worth it imo but everyone says you cant run more than a stage 1 tune without down pipes
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      03-14-2016, 06:31 PM   #13
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Quote:
Originally Posted by Kevinl View Post
Interesting you say that I am not worried about the 15 hp the down pipes add not worth it imo but everyone says you cant run more than a stage 1 tune without down pipes
Thats due to EGTs/heat. The stock DPs are not as bad as most of the close coupled cats on the DPs of most newer factory turbo cars were the cat is RIGHT in front of the turbo (where the exhaust gases have cooled and contracted none) but any restriction close to the turbo is going to cause back pressure which causes heat. When you start pushing EGTs outside the turbos safe parameters routinely your asking for failure. Stage 2 tunes recommend DPs because the removal of the restriction relieves enough back pressure to allow more boost and leaner afr without rising EGTs the way you would with stock DPs. You can run more than stage 1 tunes but you need ethanol or meth and their cooling effects to counter the effects of the stock cats on EGTa. The more ethanol and meth the more cooling effect and lower EGTs so if an ethanol tune is designed to run E40 WITH catless DPs to be safe I'd run more than e40 without DPs to accommodate the tune aggressiveness (with the appropriate scalar adjustments and fuel system upgrades of course).

Anyway you cut it though catless is better for performance and longevity.
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      03-15-2016, 05:43 PM   #14
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Quote:
Originally Posted by Kevinl View Post
I am running a JB4 with map 5 30% e85 70% 91 car has a muffler delete but is stock otherwise I plan on ordering a intercooler before summer

I am torn on down pipes I have to get emissions test every two years and the DP fix seems like a pain since it is not recommended to be left installed. I also don't want the car to smell although the mid cats should clean it up enough.
I think DP is a must for this car. They offer a lot for cheap (the sound upgrade on its own is worth it in my opinion)

That being said, i would get an intercooler first
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      03-15-2016, 05:56 PM   #15
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Quote:
Originally Posted by mike@x-ph.com View Post
I think DP is a must for this car. They offer a lot for cheap (the sound upgrade on its own is worth it in my opinion)

That being said, i would get an intercooler first
Well i just ordered both from you on sunday so i guess im covered
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      03-15-2016, 05:57 PM   #16
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Quote:
Originally Posted by Kevinl View Post
Well i just ordered both from you on sunday so i guess im covered
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      03-16-2016, 02:31 PM   #17
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Downpipes make a huge difference in my opinion but after going FBO, I realize that getting an intercooler should be always be first before you increase power output. You should be good if you keep your secondary cats in. Smells pretty bad when it's fully cattless as I just took off my secondaries.
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      03-16-2016, 05:06 PM   #18
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Does anybody heat wrap their down pipes ???? I plan on doing this or getting down pipes powder coated to reduce heat
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      03-16-2016, 05:41 PM   #19
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Quote:
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Does anybody heat wrap their down pipes ???? I plan on doing this or getting down pipes powder coated to reduce heat
I would not worry about it unless you track your car often and push it to the limit
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      03-16-2016, 05:57 PM   #20
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Quote:
Originally Posted by Flex68 View Post
Does anybody heat wrap their down pipes ???? I plan on doing this or getting down pipes powder coated to reduce heat
Not sure if powdercoating is the best method. You should seek out a ceramic or thermal coating instead.
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      03-16-2016, 06:00 PM   #21
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You get used to the smell with catless downpipes...or maybe I've just killed too many brain cells

Let us know how the install goes!
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      03-16-2016, 06:06 PM   #22
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If you keep the secondary cats it's not that bad. I've had other cars where the smell was a lot worse so it really depends.

If you don't want any chance of smell but want a bit more flow, consider a catted option like Wagner.
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Last edited by Jeff@TopGearSolutions; 03-16-2016 at 10:07 PM.
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