Which set of Downpipes?

FenFab says no defoulers in their downpipes.

FenFab says no defoulers in their downpipes.

Don’t need them with SPD either.

They are built-in to the pipes themselves. See this video at 8:10. That's an extension of the o2 sensor plug, which is a defouler.




SPD will not send them with their downpipes, but if you have a CEL pop with one of their units and email them they will send you a set. For example, here is confirmation for the F-150 kits.

See post number 8:

https://www.f150ecoboost.net/threads/spd-catted-downpipes.83758/

We simply send them as a fail-safe to avoid that step.

My question is how much hp would a set net?

I suppose I'm going to get a bunch of blowback on this, but when @Blown F-150 posts "going to depend on the tune", he means exactly that. One thing that I've learned on this forum is that not everyone understands how various components work together. A pair of downpipes bolted on a stock ST is not going to net those kinds of horsepower.

Think about this way- if you just add a tune, on 93 with a completely stock ST, you can see around 100 extra HP. If the stock downpipes were so restrictive that just replacing them would net those kinds of HP gains, how could that be the case?

The fact is that I have no doubt that less restrictive downpipes would be worth more HP- at a certain level of tune and modifications. I have in the past suggested to do downpipes if you're adding the upgrade turbos. That's just my opinion and I'll be more than happy to see you disagree...until someone shows me actual evidence otherwise.

Most of us recognize that anyone replacing the downpipes is also replacing exhaust components, and adding a tune. And when you get into that, it's completely apples/oranges. I'd also like to point out (and I want to assure you that I have no dog in this fight), if you ever want to have a warranty claim denied on something major related to the drivetrain- replacing the cats will give you absolutely no defense in trying to get something warrantied.

I only write this for those who are just picking up info from the forum and perhaps not incredibly knowledgeable about such things. That's what the forum is about, sharing information. I'd hate to see someone (yeah, it's not likely), with the bad LH cat replace the cats with aftermarket versions expecting those types of HP gains, or God forbid having Ford reject a majorly expensive engine/trans warranty claim because of it.

I suppose I'm going to get a bunch of blowback on this, but when @Blown F-150 posts "going to depend on the tune", he means exactly that. One thing that I've learned on this forum is that not everyone understands how various components work together. A pair of downpipes bolted on a stock ST is not going to net those kinds of horsepower.

Think about this way- if you just add a tune, on 93 with a completely stock ST, you can see around 100 extra HP. If the stock downpipes were so restrictive that just replacing them would net those kinds of HP gains, how could that be the case?

The fact is that I have no doubt that less restrictive downpipes would be worth more HP- at a certain level of tune and modifications. I have in the past suggested to do downpipes if you're adding the upgrade turbos. That's just my opinion and I'll be more than happy to see you disagree...until someone shows me actual evidence otherwise.

Most of us recognize that anyone replacing the downpipes is also replacing exhaust components, and adding a tune. And when you get into that, it's completely apples/oranges. I'd also like to point out (and I want to assure you that I have no dog in this fight), if you ever want to have a warranty claim denied on something major related to the drivetrain- replacing the cats will give you absolutely no defense in trying to get something warrantied.

I only write this for those who are just picking up info from the forum and perhaps not incredibly knowledgeable about such things. That's what the forum is about, sharing information. I'd hate to see someone (yeah, it's not likely), with the bad LH cat replace the cats with aftermarket versions expecting those types of HP gains, or God forbid having Ford reject a majorly expensive engine/trans warranty claim because of it.

First off excellent explanation, I am running e50 now and h pipe/ axle back. I am on the fence to go with the cvf dp’s and a mid pipe and cvf intercooler or cvf intercooler, afe front/ rear sways and fenfab toe links. Lol save some coin for the family with the intercooler and toe links. T-Mac what do you think wise one ? Btw as always I appreciate tour input!

That’s a great way of laying it out [mention]TMac [/mention]


I would have to dig around for the few examples of actual before/after Dyno results for only the addition of Downpipes. Those few had intercoolers already and 93 or better (Eblend) custom tunes. I’m not sure if you would pick up a single HP with a tune like the Ford Performance tune in the way it’s built.

Others have noted a solid 2/10ths gain on 93 in the quarter which roughly aligns with the Dyno numbers posted by a few.

I certainly don’t have the data to back it up, but IMO there are some gains to be had with a less restrictive Cat, but also with a better design of the DPs. The Stockers have such a hard 80 degree bend in them, that I can’t see there not being gains there.

Anyway, I hope to do a little before and after once my DPs arrive. I think another data point would be good for the sake of argument, if nothing else.


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Like I posted, I'm sure there are gains to be had. I'm just trying to let those who don't have your expertise know that if you're taking about stock, or near stock- they aren' worth the money. I also want to warn those who aren't knowledgeable that under the "clean hands" doctrine, if you install aftermarket cats, you're probably in a worse situation than if you have an aftermarket tune. Just something for newbies to consider.

That’s a great way of laying it out [mention]TMac [/mention]


I would have to dig around for the few examples of actual before/after Dyno results for only the addition of Downpipes.

I gained 21 HP over stock base with Steeda IC and Whoosh downpipes, no tune or intake.

I don't think the IC adds much alone on a cold dyno run. From what I've seen from downpipes, 15-25 HP seems to be the range, but it's a limited sample size.


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Do you have dyno results to share?

I'm not trying to be a jerk, but it doesn't make a lot of sense that someone with no tune- and just an intercooler and newly minted downpipes paid a couple hundred dollars for a dyno- unless they were sponsored by a vendor. If I'm wrong, I'll be more than happy to apologize, but you'll forgive me for being just a bit skeptical.

I'd completely agree on the intercooler, there is a amount of time before it gets heatsoaked, but it's great insurance for something over a 1/8 mile pull.

Regarding SPD Downpipes- they are already the most expensive option at $1,399. If you want GESI cats instead of the “highest grade EPA approved catalytic converters” then the price goes up to $2,499.

Question 1- are the standard SPD downpipes worth more than double the cost of the whoosh, CVFab or $500 more than the FebFab downpipes?

Question 2- or answer to Q1 above is yes, then is it worth another $1,000 for GESI cats? Is there that much to be gained with GESI cats versus their standard option?

LOL No, the shop isn't playing games. No, I'm not shilling for anyone. No, I didn't pay hundreds of additional dollars for a before and after dyno. I simply asked that it be added to my work list. When a shop has a dyno, why wouldn't I? I'd like to know and document along the way what parts actually have real gains. Most people just strap a part on relying on the manufacturer claims. For myself and others doing similar mods it's useful info.

I had no idea what it would run stock. I don't think I've seen anyone else run a stock dyno, at least that I was able to find in searches. So when the final torque run after the work was done I thought it was odd to only gain 4 TQ, but the HP seemed about right from what I've seen for gains claimed by those that added DPs (and vendors).

I just went by what the tech told me at the time. I'm going to have him check and trying to get the charts. I've only had a dyno on a vehicle one other time and it was 1996 so forgive me for not getting every last detail. Again, I wasn't there for the stock run but I did see the screen for the after. I don't recall what the peak HP RPM was since I was really only thinking what the max results were.

I'm just a guy who likes data and info. Not in this for sponsors, regular track runs, or to beat my chest. My only goal is to maybe hit an 11.99 on stock turbos one day without spending a bunch of money on parts that don't do much. That, and maybe shock a guy in a fast car a 5,000 pound SUV has no business beating.

ZFG tune is in my inbox and waiting to put that on. I'll be getting another dyno after I've had the revisions. Likely on a dyno day with reduced cost, though.

Only 2,665 miles on it as of today. Might wait til 5k for the tune, might not. Being cautious since it's my first turbo and want to make sure it's broken in a little.

On the shop, I will give them kudos, though. I felt the price was reasonable and they gave me a veteran discount. The shop is veteran-owned. They do a ton of high-end import and turbo work, and have done work on Billy Bart's pretty damn fast ST. (part of why I chose them) Anyone in the Orlando area should put OStar on their short list.



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