View Poll Results: Which would you choose on a stock car?
HKS DP 2.65\" $400
62
48.82%
RMR DP 3\" $325
65
51.18%
Voters: 127. You may not vote on this poll
HKS Downpipe vs. RMR Downpipe
Aug 28, 2003, 07:17 AM
#31
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Originally posted by Noize
For any that doubt this, I challenge you to find a dyno run of an RMR unit on a 400whp car and then swap the HKS part on and run them back to back. The difference will surprise you.
For any that doubt this, I challenge you to find a dyno run of an RMR unit on a 400whp car and then swap the HKS part on and run them back to back. The difference will surprise you.
However, IMHO .... at 300 whp or below, low end torque loss with a 3" dp would become more apparent then the improved top end would be. To translate, I'm stating that a 2.65" dp is MORE ideal for this application (300 whp or below), hence why HKS designed it that way. I'M NOT ... AND NEVER INTENDED TO ARGUE THAT A SMALLER DP IS BETTER IN ALL TURBO CAR APPLICATIONS!!!
You claims suggest that most evo owners are interested in climbing the horsepower latter as far as safely possible like u; however, sorry to inform u but you are mistaken if you feel this way. The truth is, most evo owners are looking for a nice power gain for the street (daily driving) use ... and 350 + whp is NOT likely a hp number that most will see, simply because the car must be reliable as many use it for everyday use.
As for me .... sure I will swap to a larger dp down the road, because I would like to make close to 400 at the wheel someday ... as i consider myself among the minority of 'daily drivers' that prefer to risk running allot of power in a car used on an 'everyday' basis.
Just remember though .... that my argument is that the smaller HKS dp is ideal for a certain applications, but by NO MEANS .... would I be so uninformed to suggest that the HKS is best for all applications .... now can all we agree on this or not?
Last edited by evo1; Aug 28, 2003 at 07:27 AM.
Aug 28, 2003, 11:53 AM
#32
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Originally posted by EVO_RPM
Do you have the JIC with the extended tip so it doesn't burn or make your bumper black?
Do you have the JIC with the extended tip so it doesn't burn or make your bumper black?
Nov 19, 2003, 05:42 PM
#33
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I sugget a full 3" mandrle unit in most cases. We offer a 3" 02 elim Turbo back that outflows anything currently on the market.
I am unaware of any other company offering such a high flow downpipe. The great part about ours is that it eliminates the restrictive stock 02 sensor housing with a 3" SS tubular unit.
I have down a lot of dyno testing with the EVO and have never found more low end power with a smaller downpipe.
We always make more power with a true 3" unit. We usually seem the same power down low and a lot more power up top. The bigger downpipe isn't going to hurt power.
We have relocated our 02 sensor from the older pic below. It is now lower in the downpipe. You cna see the design of our 02 elim where it gets rid of the cast housing.
I am unaware of any other company offering such a high flow downpipe. The great part about ours is that it eliminates the restrictive stock 02 sensor housing with a 3" SS tubular unit.
I have down a lot of dyno testing with the EVO and have never found more low end power with a smaller downpipe.
We always make more power with a true 3" unit. We usually seem the same power down low and a lot more power up top. The bigger downpipe isn't going to hurt power.
We have relocated our 02 sensor from the older pic below. It is now lower in the downpipe. You cna see the design of our 02 elim where it gets rid of the cast housing.
Dec 3, 2003, 12:23 AM
#34
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IF u plan on rocking the stolk cat. Go with the bushour 2.5 dp or the HKS cause there is no point of going from big to small to big again. It will cause turbulance and loose a bit of power sure it will make some but it wont live up to it potential.
my .02
my .02
Dec 3, 2003, 05:23 AM
#35
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Well the O2 housing change is good idea but I made my downpipe to just mate up to it for two reasons. Number one, people want something that is easy to install and with just 4 bolts, this way is easier. I made it integrated with the cat delete so just bolt onto exhaust. Secondly, the larger turbo kits usually give you an O2 housing as I know mine and many others do so no need to change one now and in fact may make it incompatible with certain turbo kits in the future. Just a few other things to consider. I woulod go 3 inch always. It's just not worth it to go smaller.
Dec 3, 2003, 05:42 AM
#36
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isnt the 2.65" on the 02 sensor housing flange and then opens up more on the other side?? just curious....I too am with the other guys, My heart is set with the HKS DP,UR 3" catdelete, and HKS 30th exhaust.
Dec 3, 2003, 06:13 AM
#37
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Originally posted by Guru
Well the O2 housing change is good idea but I made my downpipe to just mate up to it for two reasons. Number one, people want something that is easy to install and with just 4 bolts, this way is easier. I made it integrated with the cat delete so just bolt onto exhaust. Secondly, the larger turbo kits usually give you an O2 housing as I know mine and many others do so no need to change one now and in fact may make it incompatible with certain turbo kits in the future. Just a few other things to consider. I woulod go 3 inch always. It's just not worth it to go smaller.
Well the O2 housing change is good idea but I made my downpipe to just mate up to it for two reasons. Number one, people want something that is easy to install and with just 4 bolts, this way is easier. I made it integrated with the cat delete so just bolt onto exhaust. Secondly, the larger turbo kits usually give you an O2 housing as I know mine and many others do so no need to change one now and in fact may make it incompatible with certain turbo kits in the future. Just a few other things to consider. I woulod go 3 inch always. It's just not worth it to go smaller.
Does it clear the brase?
Dec 3, 2003, 06:40 AM
#38
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Yes it comes with the gaskets bolts and the spacers and longer bolts to make the braces clear. It's all plug and play. It also is integrated with cat delete so no extra flanges to cause turbulence. No CEL either and the extar bung means you can either cap off the standard O2 bung (cap provided) or use it for a wideband O2. Very handy.
Dec 3, 2003, 05:34 PM
#41
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I have the HKS. unbelieveable craftsmenship. I got mine for $300 from AM Motorsports here in MD. It is flowing to a hi flow cat and tanabe ultra medallion. Just my 2 cents
Jan 16, 2004, 09:48 PM
#42
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Re: Reply to Eric
Originally posted by Mojo Powered
Hi Eric, this is Memed, I'm a friend of Mohammad's. We had met at a dyno at BM Tranny last spring, I had my black GTI with me that day, not sure if you remember me.
Anyway, I just wanted to say a few things since I have some experience on downpipe choice myself from my car. First of all, I have to say that my K03 turbo is as tiny as a turbo can get, running at 1.3bar. You can hear it whistling from inside the cabin with windows up. So it is running at full efficiency if not slightly over. My downpipe choice was to go with 2.5inch over a 3inch because of overspooling problems with the 3inch. When you're running that much pressure on such a tiny turbo, the last you want to have is overspooling.
However, I think evo's turbo is a decent size turbo compared to k03s or even k04s. Yes, you guys are right about the possibilityof losing low end torque with a 3" but I think the spoolup is much more abrupt and quicker with much less backpressure. So yes, the boost is not phased in smoothly or as smooth as it would be w/ a 2.65". But it will definitely help you to reach full boost easier. So in my mind, it'll make up for that roughness with added flow at higher rpms.
On the other hand, there's also the theory I was discussing with that Russian guy at the dyno (sorry can't remember his name) about accelerating exhaust gas flow. That could theoretically be achieved by a decreasing diameter catback. Actually, that theory even proved itself when Mohammad put down slightly more power with his 4" to 3" downpipe to a 2.5" setup. I remember as a comparison you had a 3" full turboback with pullies and you put down slightly less that day.
As a summary, although I am not be an expert, I'm all for a bigger diameter exhaust considering that evo is not a smooth car to start with. It's running 19.5 psi stock so in my mind, it makes more sense to me to go all out and go 3". Especially, if you get a full 3" downpipe like Vishnu or AMS. Matching that with a 2.5" or 3" catback should yield even better results.
In my mind, Mohammad's 4-3-2.5 setup is definitely ideal. I wish we had such a solution for the evo. Wouldn't you think that'd be the best setup to have accelerated exhaust gas flow with the least back pressure. Remember that these are turbo engines, we don't need that much of back pressure on high revving (6K+ rpm) high boost cars.... NA engines are a totally different story.
Memed
Hi Eric, this is Memed, I'm a friend of Mohammad's. We had met at a dyno at BM Tranny last spring, I had my black GTI with me that day, not sure if you remember me.
Anyway, I just wanted to say a few things since I have some experience on downpipe choice myself from my car. First of all, I have to say that my K03 turbo is as tiny as a turbo can get, running at 1.3bar. You can hear it whistling from inside the cabin with windows up. So it is running at full efficiency if not slightly over. My downpipe choice was to go with 2.5inch over a 3inch because of overspooling problems with the 3inch. When you're running that much pressure on such a tiny turbo, the last you want to have is overspooling.
However, I think evo's turbo is a decent size turbo compared to k03s or even k04s. Yes, you guys are right about the possibilityof losing low end torque with a 3" but I think the spoolup is much more abrupt and quicker with much less backpressure. So yes, the boost is not phased in smoothly or as smooth as it would be w/ a 2.65". But it will definitely help you to reach full boost easier. So in my mind, it'll make up for that roughness with added flow at higher rpms.
On the other hand, there's also the theory I was discussing with that Russian guy at the dyno (sorry can't remember his name) about accelerating exhaust gas flow. That could theoretically be achieved by a decreasing diameter catback. Actually, that theory even proved itself when Mohammad put down slightly more power with his 4" to 3" downpipe to a 2.5" setup. I remember as a comparison you had a 3" full turboback with pullies and you put down slightly less that day.
As a summary, although I am not be an expert, I'm all for a bigger diameter exhaust considering that evo is not a smooth car to start with. It's running 19.5 psi stock so in my mind, it makes more sense to me to go all out and go 3". Especially, if you get a full 3" downpipe like Vishnu or AMS. Matching that with a 2.5" or 3" catback should yield even better results.
In my mind, Mohammad's 4-3-2.5 setup is definitely ideal. I wish we had such a solution for the evo. Wouldn't you think that'd be the best setup to have accelerated exhaust gas flow with the least back pressure. Remember that these are turbo engines, we don't need that much of back pressure on high revving (6K+ rpm) high boost cars.... NA engines are a totally different story.
Memed
I hope all that made sense. There is no one answer to whether 2.65 or 3 inches is better for the downpipe.
Jan 16, 2004, 09:53 PM
#43
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I'm looking at this poll $400 for the HKS man either prices really dropped or you shpping at all the wrong places. $300 is a good price now and $325 is about average.
Jan 17, 2004, 10:38 AM
#45
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If I am keeping the stock Cat would the HKS do the trick. Does anyone actually have any hard facts or numbers to show me which of these two DP's will flow th best while retaining the stock cat and using an 80mm cat back?