I was wondering what mid/down pipe is the best on the market. I want to keep 3" all the way back!!

The only companies I have seen that have 3" is Petitt and M2. I just wanted to see what people have bought and their experiences with different products.

I am currently debating the ecu problem: AEM or ApexiPFC? What do you think

Thanks in advance

Current Mods:
Basic Reliability Mods
Apexi GT Spec Exhaust
Test Pipe form testpipe.com
Apexi Intake

 

3" is 3". The only real differences between the M2's, Pettit's, RB's, HKS's, etc. is going to be finish (stainless or mild steel) and install (some say M2's is easier since it doesn't require removal of the studs). Aside from that, a pipe is a pipe.

 

M2 or Pettit.

 

the difference is the degree of difficulty of installation. Some downpipes, fit better than others, while some are a bitch to fit. I hear that the HKS ones fit the best out of all of them and the M2 ones fit pretty well too. As far as midpipes go you can get anyone you want if you don't care about noise. If noise is an issue get a resonated one, if that's still not quiet enough weld a borla XR1 muffler into one to tone it down even more.

 

I have m2 and it fit great and performance wise it is great. I would suggest that one and probably getting it jet coated would help with heat transfer Midpipe I think I am going to get a custom made one.

 

Does anyone have any performance info for the 3" HKS Downpipe?

I just recently bought the Titanium HKS exhaust (4") and wondered if there is a 4" downpipe avaliable???

 

4" would be a custom job. Damn shame, I'd like one.

 

4" would be a little large for the stock Twins. You sig show a test pipe? On my Eclipse a test pipe was a midpipe. It replaced that main cat with a 3" pipe. I had a Pettit DP on my FD but I just bought a FEED DP so I will be selling my Pettit here sometime soon. As far as MP's go. I went with RX7 Fashion SS 3" but I don't think it really matters aside from being resonated or not. I have the PFC which I heard was the most capable easy to tune ECU on the market. Haltech is supposed to be a PITA to install and the AEM is just to new for any real opinions. The PFC w/ Datalogit is the way to go w/ a proven track record and now the laptop capablility is available. That was my choice.

 

Downpipe: get SS, M2, Pettit, Bonez SS
ECU: PowerFC right now, AEM has no base of users yet, Haltech requires installation of all new sensors and new wiring harness

Also, have you fully researched the pros and cons of installing a midpipe? You might have too much boost creep and get large spikes, even with PFC controlling things.

 

I would agree.

 

New Question???

I finally recieved my Titanium HKS 4" exhaust This exhaust is from the downpipe back (NO cat )

I wanted to know if there is a 4" downpipe avaliable somewhere. If custom, anyone know of anyone that can make it??

I plan on running a PFC in the future along with the exhaust, intake. Any forseen problems ahead from anyone. Any other performance parts needed to avoid problems???

From what I searched on the forum this exhaust is one loud *** ************. How much louder is this exhaust compaired to my old Apexi GT Spec??

Does the 3" HKS downpipe outlet bolt up to the 4" Titanium exhaust inlet ??

Thanks for all the input
Jason

 

I am sure you could get a custom one, but no one makes and sells them as a normal item.

Yes, you will get boost creep like a **** if you are running the stock turbos. You can have the wastegate enlarged and modify the flapper door to open farther, but you will need more restriction than the 3" downpipe will give (so a 4" is probably not a good idea from a cost/benefit standpoint).

Yes, it is loud as hell and not even close to streetable, IMO. In all seriousness, you will damage your hearing with that exhaust if you drive the car a lot. The GT Spec is quite loud, too, but your new exhaust is a lot louder.

Yes, it bolts up. If you decide to have one custom made, you should get a 4" v-band setup to replace the flange. But like I said, there is no sense in making a 4" downpipe for the stock turbos because you will already be battling boost creep and adding restrictions. A 4" downpipe with a single turbo makes sense, though.

 

there is no sense in having the 4" exhaust if he has a 3" downpipe

 

There is no sense in having a 4" exhaust with the stock turbos, but it will still flow better than an all 3" setup even if only part of it is 4".

-Max

 

and why do you think that is true??

 

--------------------------------------------------------------------------------
Originally posted by maxcooper
it will still flow better than an all 3" setup even if only part of it is 4".

-Max
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and why do you think that is true??



Pousielle's Law says that maxcooper is correct.

thesaint

 

Yeah, uh, Pousielle told me it would be better. Thanks, thesaint!

Also, there are some bends in the back that will flow better if they are made with 4" pipe rather than 3" pipe.

-Max

 

ALL:

the HKS DP is NOT 3" it is only 72mm (same as stock) and uses the SAME RESTRICTIVE CASTING to mount to the turbos as the stock precat.

 

N-tech dps fit well too and they are SS.

 

B.S.

For laminar, non-pulsatile fluid flow through a uniform straight pipe, the flow rate (volume per unit time) is given by Poiseuille's Equation:
F = DP p r 4 / 8 h l.

in case you don't know what a uniform straight pipe is, that means 4" all the way through -- and you spelled Poiseuille wrong


sure it flows better with a 4" pipe than a 3" pipe, BUT ONLY IF it is 4" all the way through. look up "mandrel bent" and you will see that the bends do not inhibit flow enough to matter at all

 

The 3" to 4" junction on such a setup is way less than ideal, but I think the muffler and the mandrel bends (which are more than 7 degrees, and thus do matter, AFAIK) will make up the difference and then some.

Of course, I am not 100% sure, and it is nice to debunk or discover something that no one else saw before, but I have serious doubts that an all 3" system would flow better (under the conditions seen on the car) than one that starts with a 3" downpipe and goes to 4" after that. That's all I am saying, and I have been giving reasons. What makes you think an all-3" system would flow better?

-Max

 

I never said it would flow better, they would both flow pretty equally.