Hey guys just curious what kind of horsepower gains am I going to see with a downpipe on a stock evo running 19psi? Am I going to benifit a whole lot more by just doing a complete exhaust system instead of the downpipe alone? I'm debating on an afc or downpipe next but i'm strongly leaning to the afc, I know i'll see more bang for the dollar with that mod. Just curious

 

I would go with the AFC. You're gonna want to get a 3 inch downpipe, and if you don't do the full 3 inches at one time, it won't bolt up to the stock cat. The stock cat isn't 3 inches. I have an AFC and it's awesome. Best money I spent so far. Just my opinion

 

You'll definitely make more power with the downpipe, just depends on other factors how much more.

I have the RMR intake and downpipe and they added 30hp on the dyno. I was told by Rhys Millen that the reflashed ECU would really help cars with better intake and exhaust. He was right - after the reflash it made another 30hp on the dyno. We are guessing that after I add the cat-back exhaust, about 350hp (300 or so whp) will be on the cards.

Good luck with the mods....

 

Does RMR downpipe clear the OEM under car brace?

 

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There are gains to be made with the Super AFC but there are better options for a computer. With the Super AFC and the lack of timing control there will be knock events that you can't hear with the leaning out your A/Fs. If you can pull a tad of timing when leaning when knock happens then you can smooth out the system and not have the ECU pull timing across the board. I like the Vishnu Exed and have seen it do wonders on the WRX and just past weekend with the EVO on the dyno. With out added boost (factory boost setting) it added 17hp to the wheels. Safer and Smoother. Yes the cost is more but there are more features like more points of adjustment in the fuel map and full timing control at factory ECU settings and load points.

But the Super AFC is bang for the buck. I would suggest to do a exhaust first because there are gains to be made. And there are some great options for exhaust systems already out.

IMHO Eric

 

the exhausts out are not really options i'd like to take. i'm looking to fit my car with an HKS hipower silent exhaust or maybe a hipower exhaust, but i'm not ok with it falling short. A downpipe is in mind but right now i'm looking to increase fuel mileage and power. I mean i know with a fuel controller i can lean the high end out and save some fuel there and make power while doing it. If I do an exhaust i'm going to want to add the whole system and I don't feel there is anything on the market I like yet. As far as a vishnu system not sure about that. I was tihnking about a powerfc or something in the lines of that but i don't think something of that nature is needed. I'd like to keep my car as stock looking as possible so I can sneek a warranty inspection by when needed. Of course all parts would be removed but I don't want stock wirs cut and things tapped here and there. Which is wwhy I ordered the harness extension. But i don't know if timing really needs to me messed with i mean the only timing that i've heard complants about is the factory glitch where some cars were released with incorrect timeing. Other then that I haven't heard of timing issues and I'd rather not mess with sometihng that doesn't need to be messed with. I mena for 15hp i'd rather let my car run on the way safe side then to alter it's timing and possibley have it run 5 degrees hotter .

 

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Yet again when leaning out A/Fs there is some timing the needs to be PULLED to smooth out the map and avoid knock. So S-Afc is not per say safer. And you getting a wiring extention anyway so you can use anything you want. Yet again IMHO.

If you are worried about the dealer voiding your warrenty why would you mod your car??

My Best
Eric

 

Why would I buy this car if I wasn't to mod it? If I wanted something jsut to drive around I wouldn't have chose and evo i'd have bought a H2. Evo's aren't exactly a luxury car. I bought my car to mod and have fun with it. And if something does break I don't want to pay to replace it, would you? Which is why I'd like to retain a warranty. I mean if a part fails replace it dealers aren't loosing money infact they are making money with any work they do. Only people who loose money is Mitsu and I could give a **** what they loose.

Also why would you want timeing pulled when under boost? isn't optimal timing at around say a rough 15 degrees? What would you say is optimal timing?

 

You can't just add a number of timing and that's it. With the proper equipment you can see were there will be knock and reduce timing to compasate for it. See becuase is runing rich A/Fs they are also runing a great deal of timing to make some kinda of power out of the thing. When you lean A/Fs there will need to be some timing pulled to smooth out the TQ and HP curve. Witch is the only safe way when leaning out A/Fs. But the right tuner on a dyno will be able to program a S-AFC to run safly with the stock timing. But there is more power to be had with timing control (and safer). No such thing as Optimal timing. What I mean about this is it depends on your gas you use, how you drive how much boost you use and so one. That's why has a knock feed back system in the ECU. It knocks the ECU pulls timing. it pulls timing for safty but you also lose performance. For example the stock ecu might pull 5 degrees out a knock point were you really only need 2 degrees pulled. So you lost some power there were you could have kept it. Now adding timing at peak TQ or Peak VE is very tricky but I think (do not know for sure) there might be some room for power gain there. I'm really only trying to relay to you why having control over everything is better then just one factor. I have not tuned a EVO yet nor Do I have one now. But when I get mine (soon can't wait) will be able to understand the relationship better between Stock tuning and what can be done to make power.

My Best,

PS you live in cali and with 91 oct you will need to pull timing with leaning out of A/Fs.

 

An afc is far more dangerous and warranty voiding then a exhuast. I will bet 99% of the time the dealer will overlook the exhaust but red flag the afc.
Yes you can take the afc out but the technicians are not always stupid. It's obvious on this car it will be modded and if you melt a piston they are going to be suspicious automatically. You could probably leave the exhaust on and they won't care.

I don't know boost timing but at the top end I am willing to say you are pulling it back more than to 15 degrees.

 

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As far as I know (could be wrong) I never hear anyone adding or pull back 15degrees of timing on stock motor from the factory map at any load point. But your right melted pistion (due to high ext temps) or a banded up piston do to knock the dealer is not stupid. A rod braking on a stock car sure factory deffect or to much power. But talking to the great folks at pruven this weekend this motor is very strong. I can't wait until I start playing with my owen.

 

Is there anyway to get a 3" downpipe to bolt up to the stock cat? I would like to upgrade the downpipe and intake first, but I would like a s-afc but there is no harness for it, is there?

Thanx

 

I meant running 15 degrees at high RPM with boost not adding or subtracting 15 degrees.

 

What are you talking about! As long as the flanges match up it will fit. I am currently running a RMR downpipe with the stock cat.

 

ok i will post my question up on this thread too.... is a 3'' custom downpipe better for our car.... i have been hearing rumors i might lose power... i also been kinda confuzed as to why hks would make theirs 2.65 if 3'' would be better for our car... thoughts comments ??