Downpipe questions and comparisons

[mesarec]

Im looking to get a downpipe before i get my cobb ap and tune but not sure which dp to get. the cobb dp is 700 bucks!!whereas the corksport is 350ish. Since i have more expensive things on the horizon id like to keep my cost down but not at the expense of performance. Does any1 have info in the cobb dp and corksport dp? pros and cons?

 

[Champloo]

The two biggest differences that I note is that the COBB DP has a cat and includes the test/race/mid pipe section as well. The Corksport DP is catless and does not include the test/race/mid pipe.

 

[bacarl]

Nice thread!

There are two main differences. To start off, the MS3 exhaust has three sections: downpipe, midpipe aka race- or test-pipe, and cat-back. The Corksport is a downpipe only, meaning you have to get a seperate midpipe section (theirs costs $150). The Cobb combines the two, so it goes straight from your turbo to the cat-back.

Second, the Cobb has a cat converter, which is nice if you need to reduce emissions or just like the environment, but adds a chunk of cost.

Those are the big ticket differences, but people may also argue that the Cobb is better made. You'll also hear arguements for and against the divorced wastegate vs cast bell-mouth. Typically a divorced flow integrates the wastegate gases into the main exhaust stream more smoothly, but Corksport's design (probably due to packaging limitations) brings the wastegate flow in at an akward angle that kind of defeats the purpose.

 

[bacarl]

and my slow typing loses again!

 

[AutoEuphoria]

I have the corksport catless downpipe. No issues, good sound (not too loud), noticeable performance increase. I also have the corksport catless midpipe. Got both for less than a Cobb downpipe/midpipe, but they didn't have the added cost of the converters. Again, both look good and perform well.

 

[mesarec]

well see you can write a helpful post so in other words cobb may be best way to go even tho expensive. would the corksport dp and mp thro off a check engine? and if so is that why the sobb is more exp becasue it wont throw one due to the cat in it. goddam 1600 bucks for my spring mods ugh. (bang) nevermind after i do all this im sure ill need to get swaybars and or springs

 

[mesarec]

I have the corksport catless downpipe. No issues, good sound (not too loud), noticeable performance increase. I also have the corksport catless midpipe. Got both for less than a Cobb downpipe/midpipe, but they didn't have the added cost of the converters. Again, both look good and perform well.

i checked your mods and u have a cobb ap. yet ur only running a 13.78 with all those mods? say it aint so

 

[AutoEuphoria]

I didn't have the AP when I went to the track. I was running just a manual boost controller that was actually set for around stock boost pressures (it had been higher, but the weather made it less) on the stock tune. On that run I was making 13-15psi at the top of 4th I believe. I originally had it set for 17psi, but it was really all over the place that day. I didn't have it hooked up correctly. I don't think I had the downpipe at that time, either...can't remember. I then bought the AP and converted the boost control system back to stock, and now run 18 psi with little to no issues (sometimes it will boost more, sometimes I get a little knock retard...both are rare).

 

[mesarec]

with all that done now do u experience a lot of extra traction loss? is it a b**** to handle taking off or in the low gears. i would think wheel spin would be much more porminent

 

[AutoEuphoria]

Can't comment on that. The air and the ground got cold, so I'd be losing traction at stock levels now. Traction loss is generally always controllable, though...no matter what you are driving.

 

[mesarec]

true true. ya grounds cold now so cant tell anymore. granted always controllable. i just dont want it to be annoying when i get the mods i want. but theres always a way around traction loss.

 

[lestat13]

I have the corksport downpipe and midpipe. I got (and still get) CELs from time to time, even with the spacer for slow O2 sensor response. The car smells badly when vta and with a smoking turbo, it just makes things worse. Plus it's technically a federal offense to run without cats. I might have one welded in or swap to a cobb downpipe if I can fix my smoking problem with a catch can and heavier oil. If not, I will be using the factory downpipe. sigh.

So spend the extra $$ now to be happier with your setup later on. Plus with an upgraded intercooler I was having overboost problems, apparently from the corksport design not allowing my wastegate flapper to open fully. Go cobb and be done with it

 

[AutoEuphoria]

Plus it's technically a federal offense to run without cats

Then most of Michigan will be going to federal prison I guess. I don't have smoke so much...only a bit of black smoke when WOT from running rich. Also, no CEL's for me. I'm not running VTA, though...I tried that for 1 day and got tired of it quickly.

 

[Champloo]

How important is an upgraded intercooler if you have a downpipe? I'm planning on a downpipe but keeping the stock TMIC. Am I going to run into heat issues?
Actually, what about a fuel pump? Will a downpipe over-extend the stock (updated from TSB) fuel pump?

 

[PCspeed3]

rally sport direct . com has the Cobb DP for $625 I believe.

 

[PCspeed3]

BTW will the Cobb DP work with stock cat back?

 

[lestat13]

I don't know if it's just me, but as soon as I upgraded the intercooler I started getting boost creep almost anytime I went WOT. Just got off the phone with Derek at Corksport, I emailed cause someone said the wastegate flapper clearance would be an issue. NOPE! They did a mock up and took pictures to show that there is plenty of clearance, I am just past the efficiency of the wastegate and it needs to be ported out. Pics attached!!

 

[lestat13]

BTW will the Cobb DP work with stock cat back?

You can use just the downpipe, just the testpipe, or both with the stock catback. I have both on the stock cbe

 

[PCspeed3]

You can use just the downpipe, just the testpipe, or both with the stock catback. I have both on the stock cbe

Thanks man, Cobb's DP includes the race pipe. Does DP cause boost to spike at all? I thought that was only with an FMIC.

 

[lestat13]

When I ran (and now again) the downpipe and racepipe with stock intercooler I would see spike upto 20psi that immediately settled down to 16psi to hold. Occasionally I would creep in 5th or 6th gear, but it was hit or miss and didn't happen that often. It wasn't a big deal.

Once I added the new tmic, I started either creeping straight past 16, or spiking 20-22 and holding, scary. Talking to Derek at Corksport he said you really need to port out the wastegate cause at that point you are overflowing the wastegate. Then again, a lot of people upgrade intercoolers with downpipes and don't have any issues. I am thinking (since I am smoking anyway) to reinstall my factory racepipe (leaving the corksport downpipe) and then using the ETS 3.5 TMIC. Derek said that might give me enough backpressure to get the wastegate back into the efficiency range and should help with the smoking problem.... if you call covering it up fixing.