[Genieman]

Trying to make sense of all the downpipes and the downpipe info I see being posted.

So far I've seen:
VRSF
VM
ER
CG
AFE
Wagner
Prob missing a few...

All are posted by their respective retailers with the company's generic write-up: more flow, less restriction, x-inch input and output flanges... when looking at catted options, they all have minimal info, like "add cat?" And a price. Some provide cpsi numbers and cat diameter.

No one provides flow rates (cfm), very little info out there for comparing things. All I know is that most aftermarket cats have 200cpsi except for afe which has a 400cpsi.

Can anyone help out by providing either more info and/or a better way to compare to figure out what's good and what's better? With the ambiguous data being supplied by manufacturers and retailers, the only thing to go on is price...

[G.Newt]

I can only speak to the CG DS-1 catted DP.
It is the largest out of all of them in terms of diameter (5"). I've been running it for a little more than a year, including 8-9k miles during that time period.

No CELs ever. And with no tune (intake, DP, and catback exhaust only), I made 344 hp / 375 lb-ft of torque on an SAE dyno at sea level on 93 octane. So I'm quite pleased with how the setup has been working together.

Cost: When I purchased it last summer, it was under $700. Now, I think the cost has gone up quite a bit and I'm not sure why. At a ~$1k price point, idk if I'd get this, but at the price I got it for, I'm satisfied.

[bmw22915]

Originally Posted by G.Newt

I can only speak to the CG DS-1 catted DP.
It is the largest out of all of them in terms of diameter (5"). I've been running it for a little more than a year, including 8-9k miles during that time period.

No CELs ever. And with no tune (intake, DP, and catback exhaust only), I made 344 hp / 375 lb-ft of torque on an SAE dyno at sea level on 93 octane. So I'm quite pleased with how the setup has been working together.

Cost: When I purchased it last summer, it was under $700. Now, I think the cost has gone up quite a bit and I'm not sure why. At a ~$1k price point, idk if I'd get this, but at the price I got it for, I'm satisfied.

I second this. I have the same DP and I have had 20k+ miles without a check engine light

+ MPPSK
+JB4

=fun daily driver

[Genieman]

Originally Posted by G.Newt

I can only speak to the CG DS-1 catted DP.
It is the largest out of all of them in terms of diameter (5"). I've been running it for a little more than a year, including 8-9k miles during that time period.

No CELs ever. And with no tune (intake, DP, and catback exhaust only), I made 344 hp / 375 lb-ft of torque on an SAE dyno at sea level on 93 octane. So I'm quite pleased with how the setup has been working together.

Cost: When I purchased it last summer, it was under $700. Now, I think the cost has gone up quite a bit and I'm not sure why. At a ~$1k price point, idk if I'd get this, but at the price I got it for, I'm satisfied.

Originally Posted by bmw22915

I second this. I have the same DP and I have had 20k+ miles without a check engine light

+ MPPSK
+JB4

=fun daily driver

Not disagreeing, and appreciate the information I guess this is more of a complaint about the lack of specifications being provided for the the downpipes and their cats by all manufacturers and retailers. While 200 cell cats flow better than 400 cell cats ALL ELSE BEING EQUAL, it is possible for a particular 400 cell cat to flow better depending on overall diameter. While 400 cell cats do a better job at catalyzing exhaust particulates than 200 cell cats, it's possible for a 200 cell cat to do a better job than a 400 cell cat depending on length of cat and substrate.

Since no one is providing ALL of the particulars of the cats, it's hard to assess which has both highest flow (max power) and greatest ability to reduce smells, pollution, and highest probability of passing emissions testing.

Here is what I've gathered so far from the manufacturers who provide info, most have a 200 cell cats, AFE has a 400 cell cat. FABSpeed and Wagner have 200 cell cats with 300 cell HJS cat options... CG ds-1 has highest cat diameter at 5", most others are 4-4.5 inches in diameter. Judging based on pictures, some are longer than others while some have smoother transitions between pipe and cat...

[B58]

CG DS1 seems to be the most popular. I got mine for under $700 from ECSTuning about 2 months ago and they don’t seem to carry it anymore and the prices have gone up close to $900 or around that range on the actual CG website. My guess is because it doesn’t throw a CEL. Sounds great with my MPE and def blocks out at least 75% of the odor although you can still smell a tiny bit, but nothing insane like a cat less. I usually go with the cat less down pipes, but this time around I wanted to keep the car catted and this one does seem to be the largest on the market.

[B58]

[Nugget]

BCS in the UK make one.
100 cell cat with 40grm washcoat.

[kern417]

The reason why there isn't a lot of information is because they're all pretty much the same. The differences in flow that you mentioned don't amount to a noticeable hp gain. The main thing between catted and catless is the smell and sound.

[mike@x-ph.com]

Originally Posted by kern417

The reason why there isn't a lot of information is because they're all pretty much the same. The differences in flow that you mentioned don't amount to a noticeable hp gain. The main thing between catted and catless is the smell and sound.

+1
As long as its the same cell count

[Genieman]

Originally Posted by mike@x-ph.com

+1
As long as its the same cell count

What abt the 400cpsi on the afe?

[mike@x-ph.com]

Originally Posted by Genieman

What abt the 400cpsi on the afe?

400 CPSI is too restrictive in my opinion, you might as well just keep the stock one

[eluded]

Anyone hollow out the Oem cat

[kern417]

Originally Posted by eluded

Anyone hollow out the Oem cat

Not yet but that's what I plan on doing. It's a pretty common mod in general.

[mike@x-ph.com]

Originally Posted by eluded

Anyone hollow out the Oem cat

Originally Posted by kern417

Not yet but that's what I plan on doing. It's a pretty common mod in general.

Keep in mind that you are going to need a stock downpipe when you sell the car. Stock downpipe cost a lot more than aftermarket ones.

You are better off getting an aftermarket downpipe and keeping the stock one intact.

[eluded]

Originally Posted by mike@x-ph.com

You are better off getting an aftermarket downpipe and keeping the stock one intact.

I was curious because in certain states if you can pass a visual and ODB 2 returns no errors, you will pass smog. Your smog guy might even overlook the fact that the cat is hollowed out as long as everything else lines up.