[ES BMW]

To take care of the CEL, all you'd have to do is find a way to put the second O2 sensor behind the secondary cats. Maybe there's enough slack in the cable or an extension can be made? Removing the primary cat is where the biggest gains will be.

[CASHBY]

Originally Posted by My E90

To take care of the CEL, all you'd have to do is find a way to put the second O2 sensor behind the secondary cats. Maybe there's enough slack in the cable or an extension can be made? Removing the primary cat is where the biggest gains will be.

I already have secondary cats removed. So basicly the car wil be running striaght pipe all the way back.

[SfValley335i]

seems like theres only a small demand for downpipes... or maybe its because majority of users on this forum have no idea what it is or what it does... Kinda the same result I got in the Drivetrain/Exhaust forum.....

[bnj]

Originally Posted by SfValley335i

seems like theres only a small demand for downpipes... or maybe its because majority of users on this forum have no idea what it is or what it does... Kinda the same result I got in the Drivetrain/Exhaust forum.....

Agree, that's surprising. Especially compared to the interest towards exhausts without downpipes.

[CASHBY]

a lot of BMW owners might not be to experienced with Turbo cars since BMW just released one.... for all of us with passed turbo cars we know the power we can get from downpipes.

well even if i can get 10 people to do it, i think i can get them made for that small of a group

[jonerik26]

i'd be interested for 5 bills

[BoostedBMW]

I'm definitely interested in this also, but I know that I have so many other things to sink money into before downpipes that I don't want to commit to anything.

[all8up]

CEA3,
Am I correct in assuming that these downpipes will essentially be a catless version of the stock one? I just want to be certain this downpipe does not alter the location of the current factory flange - where I have an aftermarket exhaust (UR) connected to.

Here is food for thought.....the post down pipe cats are typically removed from aftermarket exhaust systems. It might not be a bad idea to cut the factory exhaust to re-use this section so the car appears to have cats. Granted these post down pipe cats do not have O2 sensors so I'm pretty sure the car will throw a CEL with a catless DP. Therefore, when it comes to emissions testing time hopefully there will be some sort of resistor/cel fix for the down pipe O2 sensors.

Anyways, sorry for the long post....put me down as interested. My only apprehensions is CELs and install difficulty. I've been under the car a number of times and the DP install does not appear to be very easy.

[max boost]

how difficult will it be to get to the DP? the front subframe does it need to be removed? why not pull the stock DP cut it open, gut it and reweld it?

either way 500 bucks is cool.

[topher04r1]

Cea3 Lets get a list going .... i'm down if we can keep it in the price range you suggested .. !

[SfValley335i]

Originally Posted by max boost

how difficult will it be to get to the DP? the front subframe does it need to be removed? why not pull the stock DP cut it open, gut it and reweld it?

either way 500 bucks is cool.

The point of downpipe is not just to remove the Cats... Its also to get wider piping which reduced boost lag and other things.

[max boost]

Originally Posted by SfValley335i

The point of downpipe is not just to remove the Cats... Its also to get wider piping which reduced boost lag and other things.

...a bigger diameter DP really wont help. now if you start playing w/larger turbos then it possible..

[SfValley335i]

Originally Posted by max boost

...a bigger diameter DP really wont help. now if you start playing w/larger turbos then it possible..

Why wouldnt a larger DP help?

[Cornhusker]

Count me in for 500-650. Assuming there's a fix for the o2 sensor thingy and there are at least some modearate dyno gains.

[max boost]

Originally Posted by SfValley335i

Why wouldnt a larger DP help?

then why not make them 5 inch then...

i believe that the majority of the benfit w/aftermarket dp is the fact that they will be catless and therefor reduce backpressure.i maybe wrong but i myself use STOCK EX PIPE ON MY TURBO C5 VETTE AND IT TRAPS 145.5!

i also think that a cat back system will alos become more effienct when cupplied w/dp.

just my .02



[IMG][/IMG]

[SfValley335i]

Originally Posted by max boost

then why not make them 5 inch then...

i believe that the majority of the benfit w/aftermarket dp is the fact that they will be catless and therefor reduce backpressure.i maybe wrong but i myself use STOCK EX PIPE ON MY TURBO C5 VETTE AND IT TRAPS 145.5!

i also think that a cat back system will alos become more effienct when cupplied w/dp.

just my .02

5 in. DP would be too extreme and kill all the backpressure. Same reason why no one puts 5inch exhaust on their cars.... Bigger is better but too big isnt good. Thats why you see 3inch DP's.

Just based off what Ive seen on different forums. They always create larger DP's thus theres a reason why they do that, more power.

As Ive said in the past, exhaust and DP's alone wont help as much as it would if theres a specific TUNE for it. And not a tune from a Vishnu/RD sport/AA but a tune specifically for your motor.


Cea3 did you get a chance to get more info for us yet?

[BoostedBMW]

Since when is back pressure good for a turbo car? I think you don't see larger DP's due to clearance issues, not because they want more back pressure.

[max boost]

Originally Posted by SfValley335i

5 in. DP would be too extreme and kill all the backpressure. Same reason why no one puts 5inch exhaust on their cars.... Bigger is better but too big isnt good. Thats why you see 3inch DP's.

Just based off what Ive seen on different forums. They always create larger DP's thus theres a reason why they do that, more power.

As Ive said in the past, exhaust and DP's alone wont help as much as it would if theres a specific TUNE for it. And not a tune from a Vishnu/RD sport/AA but a tune specifically for your motor.


Cea3 did you get a chance to get more info for us yet?

all i am saying is that the majority of the benefits will most likely come from the fact that it is catless. now as far as most dp being larger then stock, theres marketing involved in that. who would buy company's X dp if it was stock size over company's Y dp that is larger?

[max boost]

Originally Posted by BoostedBMW

Since when is back pressure good for a turbo car? I think you don't see larger DP's due to clearance issues, not because they want more back pressure.

never said it was.....the cat is causing more bp then the diameter is.

[eshtog]

Originally Posted by max boost

never said it was.....the cat is causing more bp then the diameter is.

You are wrong a 3" down pipe will produce more power then the stock diameter downpipe.

[NPDAN]

Im in....

[SfValley335i]

Originally Posted by BoostedBMW

Since when is back pressure good for a turbo car? I think you don't see larger DP's due to clearance issues, not because they want more back pressure.

If some back pressure isnt needed. Then can you explain why exhaust manf. like borla etc use 2.5 inch piping and not 4"???? since the 4" piping would reduce back pressure greatly?