legacycentral bbs

ive been deciding on my exhuast, been researching alot, reading the forums its seems to be a vauluble thing but everyones differnt. witch downpipe. 4 inch to 3 inch bell mouth, 4- 3 inch bel with divider, 3inch and 1.5 inch separated to 3 inch or like bosal 2.5 and 1 inch separated to 2.5?horse power trying to reach is 300- 350.i heard the bell mouth dont flow so well. And the separated is not so good because difference in heat betwwen the two exhuast(wastgate and exhaust). any dyno would be great orif you had the chance to compare

bell mouths aren't bad. If you do go with a bellmouth get a divider plate put in to help eliminate turbulence with the exhaust gasses between the main turbo outlet and waste gate.

Make sure the divider is meant for your turbo, the depth can change quite a bit between models.

I run a twin dump (divorced wastegate) that is ceramic coated and it absolutely kicks ass! I would put it up against any other style DP and expect it to be better.

The problem is, if you go with a twin dump you need to be really carefull not to get a shitty one. It is the hardest style DP to manufacture and needs the highest grade materials too. There are some crappy ones on the market (like BPM) which are putting a bad name on them and one article by Cobb tuning that everyone seems to love to quote that says they can be too complicated and be so good at their designed purpose that the wastegate can flap open before it is supposed to keeping the turbo from hitting full boost (a problem I've yet to ever have). And IIRC the same article also states that if done properly the twin dump has the best flow characteristics and power gaines

I love my C.E.S. twin dump and recommend them to everyone. Here are a couple picks.

Mine looks a tiny bit different then this one but this is a C.E.S. WRX twin dump


Another shot


Another cool thing about the C.E.S. DP is they use a Boost Enhancement Plate (BEP) that goes between the DP and turbo like a gasket and are specific to whatever turbo you're running. So if you change your turbo, to like a VF23 or something, you can just order a BEP for that and be sure to have the proper separation.

Hey Matt, out of curiosity I was wondering why you think the BPM is such a bad downpipe. I've heard otherwise from several sources. Not many people have them over here since they are from over seas, so they aren't that common. I was just curious what you've heard about them. I've been thinking of going with them, but if you have good reason not to I'd like to know.

georryan wrote:Hey Matt, out of curiosity I was wondering why you think the BPM is such a bad downpipe. I've heard otherwise from several sources. Not many people have them over here since they are from over seas, so they aren't that common. I was just curious what you've heard about them. I've been thinking of going with them, but if you have good reason not to I'd like to know.

I heard from Shik at the East coast shootout last year that a couple guys that were running them had them literally fall apart. If you look at the CES DP then look at the BPM DP you'll notice that they look EXACTLY the same. This is because BPM took it's design from Trevor Miles (C.E.S.) . I don't know the whole story but BPM was licensed to use Trevors design and supply the Euro and US markets but they weren't building them to the specs that were set up by CES and so the BPM DPs' were having severe quality problems (cracking and warping) and so CES took BPM to court for contract breech or something. So the whole reason C.E.S. exhaust systems are starting to show up outside of Australia is because BPM dropped the ball and put out crappy product. All this crap went down a couple years ago so BPM may have their shit together now, I don't know, but if you're hearing good things about them then maybe they have.

holy crap. Thanks for the info Matt. I don't know if they have their stuff together yet nor not. That's some good info, though. I just know a couple guys who run them and have liked them so far. I do know that I can get a turbo back exhaust from them for about 1200, which is less than the ces one, but if the ces is better then I'd much rather be safe than sorry. Definately things to consider.

I recently installed a PDM divorced wastegate twin dump on my Legacy. YOu can see it here... http://bbs.legacycentral.org/viewtopic.php?t=14637

I don't think they are available anymore. PDM has had some issues and shut down shop for a while. Who knows if they will be back or not.

As for the Cobb article...One thing Josh says is their design will likely not be a twin dump because of cost constraints. He does say when properly designed they do produce the best gains, but they are expensive and hard to get right. And twin dump or not, the splitter does need to be matched to your turbo for the best performance. More than one person has had there wastegate stuck open by the splitter on a poorly designed DP.

My GF has an MRT full turbo back on her car. It has the cat in the DP if that is a consideration for you. Also, Stromung has just come out with a 2 piece DP that is twin dump. The second piece gives you the option of using a treack pipe or a high flow cat at the bottom. But keep in mind that none of the DP's I have mentioned are designed for the LEgacy and a custom midpipe will need to be made to fit one on a Legacy...

Thanks for the info Matt. I knew that there were some other divorced downpipe makers out there, although I didn't that those you mentioned there made some for subaru. I'm assuming they are wrx downpipes your talking about for the most part.

Even though I already purchased a perrin twin dump I honestly feel that the divorced bell mouth is the best design.

I have spoken with a variety of different people and most often they agree. What would be cool is to get some cheapo bell mouth and use the plate in the third image of legacy92ej22t's post!

which companies sell a divorced bell mouth?

I think when all things are said and done, I'll probably be getting a CES system. I was going to go with the BMG....hahaha, I mean BPM exhaust, but I'm starting to thing hte CES is a better route. I've been emailing Jeff Mills from MSR the last couple days and he has been very informative and helpful. Also he has been very prompt in his replies. I like that in a company.

Jeff Miles is a good guy and I love my CES turbo back. I don't think you will be dissapointed

Just curious, which system are you looking at, the street or race?

Right now I'm thinking street. They both come with the high flow cat, and the only difference as far as I can tell is that the street comes with a resonator. After talking to him about it I think I'd like to have one installed. He said that it helps keep the noise down when cruising on the freeway, but it still has a really great sound under throttle and high rpms. I think I'd almost want to go that way rather than have a loud muffler and cap off the noise with a silencer and lose power also.

That's what I'm thinking right now. How do you like yours? Did you get the street or race? Or some concoction of your own?

georryan wrote:Right now I'm thinking street. They both come with the high flow cat, and the only difference as far as I can tell is that the street comes with a resonator.

Hmmm...As far as I know the Race doesn't come with the resonator OR high flow cat, it comes with a race pipe instead. This is off their web site:
*Race Systems do not include cat or resonator for a slightly more agressive sound and a marginal increase in power.

I would double check with Jeff about it before making your decision

That's what I'm thinking right now. How do you like yours? Did you get the street or race? Or some concoction of your own?

They offer two different DPs. The DP01 which has a 2" main dump that slow tapers to 3" (the one pictured aboved) and the DP03 (the one I have) which has a 3" main dump all the way. The wastegate dump is 1.75" on both IIRC. IIRC both Legacy systems come with the DP03 and are prebunged for the O2 sensor so you won't have the issues I currently have with mine. I extended my wiring and put it were the wrx has theirs by the cat. Now the wiring is shorted and I have to move it . I would ask Jeff which one you'd be getting just to be sure.

I got my system before they offered Legacy systems so it is a modified WRX system. At the time it was kind of a hybrid because I have the DP03 DP ( comes with the wrx race, the DP01 comes on the wrx street) but then it's a street system cat back. I do have the resonator and high flow cat. The sound is really nice with the resonator, loud and aggressive but not too loud. It's just right. I absolutely LOVE my system, that's why I've been so vocal about it. I seriously think CES probably has the best systems available on the market.

Oh, if you want I can send you some pictures of my system with the DP03 DP and stuff. Just PM me your e-mail address.

georryan wrote:which companies sell a divorced bell mouth?

The MRT one I mentioned is one...

Hmmm...As far as I know the Race doesn't come with the resonator OR high flow cat, it comes with a race pipe instead. This is off their web site:

Yeah that's what I read on the site also, but in one of hte emails he mentions that they both come with high flow cats. Although, in his latest email i just got he mentions the street system without the cat or resonator is really aggressive sounding, but too loud for freeway driving. So maybe it was just a mistype.

The MRT one I mentioned is one...

Thanks I'll look it up. Although I'm thinking quite seriously about the CES downpipe. When I do get one, probably in the next six months, it will probably be from there, but it doesn't hurt to shop around.

Hopefully I'll be able to get my intercooler in another month.....I can't wait.