3.3TT Downpipe/Exhaust components

[KSGT1]

I've read through several different threads now and I wanted to confirm that what I'm understanding is correct as I look to upgrade my exhaust.

First, am I correct in thinking that the aftermarket downpipes all connect after the primary cat which lay directly after the turbo? It seems most of the aftermarket downpipes have the secondary cats removed except for Ultimate Performance which has a high flow cat it seems based on the pictures. Is this correct? The other thing I get confused about is this "mid pipe." It seems that the downpipe connects to the cat back exhaust and I don't see another pipe in between there. These mid pipes are just downpipes cut into two different pieces I guess?

My last question is regarding the restriction of the stock exhaust system. In a WRX STI, the most restrictive part is the stock downpipe by far and so this is what I changed out as I was after more performance rather than sound. Is this also true in the Stinger's case? I remember seeing some pictures a few weeks ago that confirmed this but I can't find that thread anymore.

 

[DiabloStinger]

Our cars have four cats.. two primaries are connected to the ecu and the two secondaries (midpipes) are not. While the most restrictions are in the primaries, they are costly, difficult and require a pro tune from lap3 currently.
Most bang for your buck is midpipes.

I'd opt for jb4 unless you just want the extra sound.

 

[Kazz]

The following assumes we're talking about the 3.3TT Stinger. I'm not familiar with the exhaust system of the 2.0T Stinger.

The pipe leading from the exhaust manifold that includes the first or "primary" cats is properly called the downpipe. The pipe that connects to the downpipe, includes the secondary cats, and connects to what's usually called the "axle-back" portion of the exhaust system is properly called a "midpipe".

Only the primary cats have O2 sensors. Any modification of the downpipe or the cats in the downpipe may require fooling of the ECU and/or "defoulers". Removing the secondary cats will not create a "Check Engine" light. While the downpipe certainly has restriction, replacing the midpipe is easier, cheaper, and reportedly can add up to 30hp on stock tune. On stock tune, an axle-back replacement without replacing the midpipe doesn't offer much, if any gains.

There is some discussion about whether the midpipe replacement yields any gains on a tuned car. Some claim that if you're going to tune your car, the replacement's unnecessary. Once you lay eyes on the midpipe back, however, it appears there are gains to be made if both the midpipe and axle-back is all replaced with a less restrictive system. We really don't have anything definitive that I've seen that has those answers.

Hope this makes sense. It's still a bit early to have definitive answers. We should have more info soon.

 

[DaBears4Lyfe]

Dont remove the primaries unless you have an actual ecu tune lines up. Trust me it's a ton of headaches. Not worth it and you will not be able to use any of the gains lol.

 

[Oryan]

Ultimate Performance is so far the only company that gets rid of all of the stock cats. It bolts to the turbo and has two HFCs shortly off the turbo. They're 400 cell cats..which is a bit dense for something aftermarket but I don't think anyone on the stock turbos is going to notice. The only gripe I really have with them is that the opening to the turbos is just round and doesn't line up with the opening coming off the turbos. But again, something I don't think will really matter until you're chasing every single pony.

Pretty much any catback is gonna give you the same gains. They're almost all just 2.5" mandrel bent pipe with resonators and mufflers. Pick the one that you like the sound of at the price point you like and go at it. From a performance standpoint they won't offer too much until you start working your way upstream.

Like others have said, the midpipe is probably the best bang-for-buck mod for power you can do that doesn't alter the ECU. Easiest to install, won't cause a CEL, doesn't need a tune to show decent gains, and unless you're in hippieland on the west coast or have similar inspection laws, won't give much issue with inspection or cause a big fuss at most(MOST..some will cry if you even change the damn air filter) dealers.

You need a tune to run downpipes on this car, period. The stock tune will bitch something fierce with no cats. Even then some tunes or piggybacks won't help much, at least not now. The only option ATM that has almost no issues is the Lap3 Pro-Tuner. The JB4 can..but some people still occasionally get overboost codes on it. Tork has been working on it but haven't seen anything concrete one way or the other. In the next few months I'd expect those and others coming to market with tunes(Hopefully..) in the near future to be able to address this and actually pull some gains out of catless or HFC cars.

All that being said...Engines are air pumps and can only move as much air through as the most restrictive area. Opening up the exhaust will only do so much if the car is still choked at the intake, and vice versa. Haven't seen it yet on this car but it isn't uncommon for boosted cars to show gains that more than equal the sum of their parts via breather mods by freeing up both the intake and exhaust.

 

[MrSmoofy]

I thought I saw somewhere that some downpipes or with the JB4 and downpipes you wouldn't get a check engine light

 

[mhal8876]

I thought I saw somewhere that some downpipes or with the JB4 and downpipes you wouldn't get a check engine light

I have DP and No CEL!!!

 

[DaBears4Lyfe]

I have DP and No CEL!!!

Downpipes or midpipes. Theres a difference and for some reasons the stinger community wont catch on. Downpipes come off the turbo. So you are saying you dont have primary cats and arent throwing a code if you are, you're the first american to do so with the jb4 lol.

 

[mhal8876]

Downpipes or midpipes. Theres a difference and for some reasons the stinger community wont catch on. Downpipes come off the turbo. So you are saying you dont have primary cats and arent throwing a code if you are, you're the first american to do so with the jb4 lol.

I got the SSR DownPipe and i don't see CEL on my dash.

 

[DaBears4Lyfe]

I got the SSR DownPipe and i don't see CEL on my dash.

That's a midpipe -_- that's why you dont throw a cel the secondary cats on the OEM midpipe dont have an 02 sensor

 

[mhal8876]

That's a midpipe -_- that's why you dont throw a cel the secondary cats on the OEM midpipe dont have an 02 sensor

I know. And why in the hell they sell it as Down Pipe? Not midpipe. It should be called power pipe lol.

 

[pgeneste]

I got the SSR DownPipe and i don't see CEL on my dash.

Hi mhal8876,
Question for you, do you have a RWD or AWD GT1 and if you look at the side of the car are the tubes of the SSR pipes flush with the underside or do they stick out (down) some, if so how much? Thanks for the feedback...

 

[mhal8876]

Hi mhal8876,
Question for you, do you have a RWD or AWD GT1 and if you look at the side of the car are the tubes of the SSR pipes flush with the underside or do they stick out (down) some, if so how much? Thanks for the feedback...

I got RWD GT1. looked at it today it just stick a little bit like 1/2-1 inch and i'm lowered on Eibach Springs too.

 

[G-160737]

Dont remove the primaries unless you have an actual ecu tune lines up. Trust me it's a ton of headaches. Not worth it and you will not be able to use any of the gains lol.

best said

 

[theoreck]

I thought I saw somewhere that some downpipes or with the JB4 and downpipes you wouldn't get a check engine light

That's because people don't know the difference between a "down pipe" and a mid pipe. Downpipe from turbo will delete the primary cats and Yes cause CEL if no tune. Midpipes connect to this inbetween the exhaust and down pipe. Midpipes will remove the secondary cats, and most likely not throw a CEL code. It's confusing a lot of people because the "Cat Back" exhausts only go from the secondary cats back, not the primary cats like many other cars that DONT have a secondary cat.

 

[Kazz]

I don't believe that's correct. IIRC, the downpipe does house the primary cats but the mid-pipe does not contain the secondary cats. Those are after, then the axle-back.

The reason I think that is because I jumped on a replacement mid-pipe when it first came out and that did not remove any cats.

 

[BIG-D]

Correct...