Downpipe or stock DP ?

[anthmash]

I recently just picked up a 2006 ms6 and il loving it to death. It's a fast car but there's always room for improvement and so the modifying begins lol. I already have the corksport Sri+TIH, autotech HPFP, and Cobb AP running a stage 2 ots map. Other modifications I've done are muffler deletes just to get a nice sound but now I'm after more power in my list for wanting more and I figured a downpipe would be the best thing to get next as I'll see the most power gains there, but I'm worried that even if I get a high flow catted DP I won't pass emissions, since it's removing both cats and replacing it with only one. So I was wondering if anyone has gone down the route of catted downpipes and still been able to pass emissions ? Not to keep the environment happy, just so I don't have to swap out every 2 years lol


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[ms3rick]

Find a smog guy....

[Spectrix]

At your point, power is going to come more from ignition changes than hardware.

For your money, a test pipe, some E85 and an e-tune from one of the capable tuners on this forum would net you infinitely more power than a catted downpipe on its own. It's much easier to swap out for emissions too.

[anthmash]

Originally Posted by Spectrix At your point, power is going to come more from ignition changes than hardware. For your money, a test pipe, some E85 and an e-tune from one of the capable tuners on this forum would net you infinitely more power than a catted downpipe on its own. It's much easier to swap out for emissions too.

I was thinking about a test pipe too, the sure m6 test pipe is what I would get. Any noticeable power gains or just frees up restriction ?


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[jk_ms3]

Originally Posted by anthmash I was thinking about a test pipe too, the sure m6 test pipe is what I would get. Any noticeable power gains or just frees up restriction ? Sent from my iPhone using Tapatalk - now Free

Please don't get Sure crap. Do a quick search to see what an awesome company they really are. Your best bet is to donate and pick one up for cheap in the for sale section.

(Also, I understand the irony of me saying that, seeing as I have a Sure TP on my car, but I got it used from a local. It's a nice pipe, but I'm not sending any of my money to Sure or Street Unit.)

[CWP_MS3]

E85 and tune. DP won't make you go fast on an OTS map. E85 + DP, and no we're talkin...

[Code Monkey]

Just buy a used OEM TP and gut it, swap in the catted OEM come inspection time.

[Turbo_Steve]

Depends on what state you are in. If they do a visual inspection you will fail. If they just scan for codes you can make it pass.

[anthmash]

Originally Posted by CWP_MS3 E85 and tune. DP won't make you go fast on an OTS map. E85 + DP, and no we're talkin...

I can't get my hands on e85 where I am, it's to much of a mission to go to the closest gas station that supplies it so that's out of the question, maybe WMI would be a god way to go but I'm not sure if i have to upgrade the top mount or might as well go fmic for that


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Originally Posted by Code Monkey Just buy a used OEM TP and gut it, swap in the catted OEM come inspection time.

If I get a TP I plan on swapping it come inspection time anyway lol


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Originally Posted by jk_ms3 Please don't get Sure crap. Do a quick search to see what an awesome company they really are. Your best bet is to donate and pick one up for cheap in the for sale section. (Also, I understand the irony of me saying that, seeing as I have a Sure TP on my car, but I got it used from a local. It's a nice pipe, but I'm not sending any of my money to Sure or Street Unit.)

As I have a totally stock exhaust (minus muffler deletes) would it be a good idea replacing just the midpipe to a 3 inch TP (using sure as an example, or even CS) if the exhaust goes from 2.5 to 3 back to 2.5 ? Or would a catback exhaust make sense pairing it to a test pipe for that reason ?


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[Spiral1183]

Just so I'm understanding, are people saying a dp isn't worth it over just a tp? I'm about to pull the trigger on a long catless dp, but if a tp will get me equal gains I don't see why I shouldn't go that route

[JgamB]

Originally Posted by Spiral1183 Just so I'm understanding, are people saying a dp isn't worth it over just a tp? I'm about to pull the trigger on a long catless dp, but if a tp will get me equal gains I don't see why I shouldn't go that route

That was my conclusion after a good bit of research as well - no regrets now that I'm tuned. No busted O2 sensors / CELs / bitch bolts to get go / exhaust stank in the car / super fast stock out.

The UR test pipe I bought through Edge was superb workmanship, and I wanted the hangers.

[Fail_6]

TP is NOT equal to a DP. I'm not sure where that consensus is coming from.

Test pipe merely replaces a section of the full stock DP, but the cat is still present, and arguably that's the biggest restriction present, other than the smallish piping. The DP upgrades to a hi flow cat, or no cat at all, and increased diameter increases the air flow path. I'm not sure if people are actually suggesting a test pipe would provide the same flow increase, but it does not.

Regardless, though I can't speak for the cats installed on CPE, ATP, etc DPs, I had an aftermarket Random Technology cat iinstalled on my existing catless DP for optimal catted results, and passed the emissions test fairly easily.

I've attached pictures of the section the test pipe replace vs a full aftermarket DP, as well as the stock cat vs the Random Tech cat

[MizzyMS3]

^^ we know a dp does not equal a tp when it comes to replacing actual hardware. They mean that they can get 90% of the performance for 10% of the headache of install and not have to worry about emissions

[anthmash]

Originally Posted by MizzyMS3 ^^ we know a dp does not equal a tp when it comes to replacing actual hardware. They mean that they can get 90% of the performance for 10% of the headache of install and not have to worry about emissions

Thank you for clearing that up lol I don't want people being confused, the option of a tp was presented to me and I am now leaning that way but one of my questions still exists, if I go to say a 3 in TP should I go ahead and do a 3 in catback as well ? That's where I now need clarification. To me it would seem that it would make sense because having the stock 2.5 in dp go into a 3 in TP and back to the remaining stock 2.5 exhaust would create back pressure of some sort


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[Dizzy Turbo]

Fwiw, I gutted both stock cats and haven't gotten a cel

[anthmash]

Originally Posted by Dizzy Turbo Fwiw, I gutted both stock cats and haven't gotten a cel

Cel isn't what I are about, I couldn't care less if I got one it's the fact of if I were to get a catted 3 inch DP I would like to know if I could pass emissions with just that. But now after some convincing I'm turning away from that and considering a test pipe with a 3 inch catback instead, so that come emissions check time I can swap the TP for the stock cat and change them out again after I pass


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[Dizzy Turbo]

Well the cel is what makes you fail emmisions, so you saying you wanna pass emmisions one would assume you care about cels...

[anthmash]

Originally Posted by Dizzy Turbo Well the cel is what makes you fail emmisions, so you saying you wanna pass emmisions one would assume you care about cels...

I realize that but if I get a cat I won't have one if I decided to go cat less I would but that's irrelevant because I'd fail like that anyway. The reason I don't care is as follows, for example, if I went only a test pipe and for some random reason I get a cel I wouldn't give a shit because I know it's from the tp. But the cel due to that is irrelevant because when it comes time to get an emissions test I will swap out the tp for the stock catted mid pipe and swap back after the test is done


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[Agent_Orange]

For people that are worried about emissions and inspection and have no plans of BT a test pipe should suffice for your power expectations. An upgraded tmic or big core fmic is a good idea as well if you really want to maximize flow on the k04.

I say FYIN.

Fuck your inspection niggah. Find a guy for that (not hard) and just go full catless.

[Dizzy Turbo]

I'm just trying to tell you that my car is catless and I passed emmisions fine, that is all.

[KusteLokal]

Op what state are you in?

[jk_ms3]

I just have the 3" test pipe with a stock dp and cbe, and I really like it. I noticed a good deal more power with it and an S-OTS tune (which really is where your gains are going to come from). When I eventually change out the cbe I'll probably do the dp with it, but for now I like this setup just fine. You're not going to see all of the power gains of a full dp, but it's WAY easier to change out if you're worried about emissions.