Are all downpipes roughly equivalent performance wise?

Agentlongwood · July 28, 2017, 08:12:05 AM

Assuming you are comparing catted to catted and non-catted to non-catted, is there any performance difference between the few different companies offering downpipes for the SHO/MKS? I know of OBX, Stainless Works, PPE, and Livernois. Do all the brands offer about the same power gains?

StealBlueSho · July 28, 2017, 09:09:03 AM

Assuming they are all the same diameter then yes, the difference between them is negligible. The PPE might be a couple HP lower because their catalytic converters actually allow you pass readiness, or so the word on the street goes... if you need cats then PPE is the way to go....

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sholxgt · July 28, 2017, 09:17:14 AM

I agree with SBS on all accounts.

They should all be similar in performance with the PPE catted probably the lowest in gains.

That being said, the other catted options don't make any sense to me. I see little value to cats that aren't within the tolerance thresholds of the stock programming. I have run the PPE catted for 20,000 miles without a tune with no CEL. Any others will have a CEL, meaning that it would not be advisable to take your car to the dealership for warranty work with them. Mine has been multiple times to the dealer with the PPE catted and they are none the wiser since there's no Check Engine Light on.

Any other downpipe option requires disabling the reading from the O2 sensors in order to keep the CEL off. Problem there is that it's a major no no to take your car to the dealership with a tune loaded. Even if just for an oil change or tire rotation, I would not take my car in tuned. Too risky if you want to maintain your warranty.

Without warranty, I would go catless, turn off the O2 sensors and enjoy the extra power.

EcoPowerParts · July 28, 2017, 09:43:56 AM

Just remember guys I made 600WHP on the catted PPE pipes, more than you'll ever dream of likely.

StealBlueSho · July 28, 2017, 09:54:12 AM

EcoPowerParts: The only reason I run catted pipes that don't pass readiness is because in Virginia and the county I live in, they do not require emissions testing HOWEVER during the safety inspection they do a visual confirmation that the cats are there...

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EcoPowerParts · July 28, 2017, 10:28:57 AM

I'm saying you're not going to be seeing a real difference between the pipes, there's no proof of that other than conjecture. Nobody has done back to back dyno testing between the pipes. On my side I know even if it is 5HP you're not going to be able to appreciate that difference in the 1/4 mile, 1/2 mile etc. etc. If you do want to make a big difference put a cutout pre 3rd cat to bypass the factory or aftermarket exhaust, that I've seen a solid .2 in the 1/4 mile.

TopherSho · July 28, 2017, 10:36:11 AM

I REALLY want to put in a branch so i can run open pipes on the back half on track days,..

StealBlueSho · July 28, 2017, 11:02:28 AM

Quote from: EcoPowerParts on July 28, 2017, 10:28:57 AM
I'm saying you're not going to be seeing a real difference between the pipes, there's no proof of that other than conjecture. Nobody has done back to back dyno testing between the pipes. On my side I know even if it is 5HP you're not going to be able to appreciate that difference in the 1/4 mile, 1/2 mile etc. etc. If you do want to make a big difference put a cutout pre 3rd cat to bypass the factory or aftermarket exhaust, that I've seen a solid .2 in the 1/4 mile.

Ever played with the boost activated bypass setups?

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EcoPowerParts · July 28, 2017, 11:32:07 AM

This is my Flex back in the day:
https://www.youtube.com/watch?v=48WlWGK2o9E

I later had this custom one made, tried to reproduce it but just wasted $2K trying to get it done.

http://www.ecoboostperformanceforum.com/index.php?topic=2191.0

Agentlongwood · July 28, 2017, 01:11:31 PM

I live in Florida so emissions testing is non-existent. I'm at about 62k miles now, so when I get around to down-pipes I will likely be out of warranty. In all likelihood I will go catless, and just wanted to check that they were all more or less the same, in terms of performance.

SHOdded · July 28, 2017, 03:29:54 PM

Performance msy be similar, but certainly not sound. With SW you have to pair DP and turboback carefully.

EcoPowerParts · July 28, 2017, 07:24:53 PM

Catless pipes are basically all the same

I pretty much don't carry them as the PPE stuff is made really nice so they charge really nice prices.

Agentlongwood · July 28, 2017, 11:35:26 PM

As far as sound, I plan on leaving the rest of the exhaust stock. Any Downpipes that should be avoided because they sound terrible with the stock exhaust?

sholxgt · July 28, 2017, 11:44:13 PM

Quote from: Agentlongwood on July 28, 2017, 11:35:26 PM
As far as sound, I plan on leaving the rest of the exhaust stock. Any Downpipes that should be avoided because they sound terrible with the stock exhaust?

Pretty sure any of them will be fine. I'd say you're on the right track also. The rest of the exhaust provides minimal gains at normal power levels and I don't find any of them to exactly sound terrific. Granted, I'm not a huge fan of the sound of most v6's, so I may not be the best judge.