My exhaust dump
 

Long story short, lets see the pic.

http://img54.imageshack.us/img54/8014/20090207172.jpg
http://img54.imageshack.us/img54/2371/20090207173.jpg
http://img18.imageshack.us/img18/4488/20090221181.jpg
http://img19.imageshack.us/img19/7627/20090221182.jpg

I forgot to take a pic when it's all welded up and installed on the car, but it's a good fit.
btw, the dump goes back to the right side exhaust tip, it was my friend's idea and it seems to be pretty good and clean. The exhaust valve is connected to the same vacuum source as the vfad at the front, it's been tested, it will open right at 5500rpm, and close when get back down to around 5k rpm.

http://www.youtube.com/watch?v=llp2pKO_UNk

here is a video

Update pic with it on the car (don't mind the ugly welds or the spray paint.....or the slight exhaust leak, i will try to fix it later)
http://img9.imageshack.us/img9/9558/20090303183.jpg
http://img113.imageshack.us/img113/8858/20090303186.jpg
http://img141.imageshack.us/img141/2294/20090303188.jpg
http://img141.imageshack.us/img141/9919/20090303189.jpg
http://img141.imageshack.us/img141/8861/20090303191.jpg

holy raspiness

i guess almost t-boning that SUV was funny...

as for the exhaust mod, that sounds like a lot of work for something that sounds like ass and improves performance very little

my friend was driving :uhh:
that's how rotary sounds like anyway, but any opinion is well come, rather you like it or not.
I just like to try things out, at least i know i can do it, or make things rather then paying 600bux+ for an exhaust that's also dont' improve much performance....even it sounds like ass to some people...:lol2:

not true.

https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/different-kind-exhaust-modification-164090/

what's not true?

Trustbuddy also has an exhaust cutout and in the thread he linked to there is a dyno run that shows about a +10 HP gain. if you can live with the noise and attention its a cheap mod.

it's funny how after trustbuddy posted up dyno numbers, all the haters just kind of shut up....

because the haters had nothing better to do then post about things they don't know anything about.

I kinda dig it. Its like nitrous with a WOT switch, power when you need it, nothing else is changed when you dont.

so its nice and quiet til 5500rpm? ....I like this idea, I have sr exhaust right now, but its still restrictive.......only problem is every honda will think i have vtec or some crap, you know how they sound, quiet till 5 or 6 grand then they sound like a rattle can on roids.

you did a good write up.

also to the OP, where did you get the materials for the valve and such?

I have no cat, so it sounds just like a stock exhaust with no cat when under 5500rpm. I just put a switch between the vacuum solenoid and the pcm, since the pcm controls the ground to the solenoid. pcm will ground the solenoid after 5500rpm. By having that switch, i can keep the vfad and the exhaust dump close for street/normal driving. Once i close the switch, the vfad and dump will open at 5500rpm by the pcm. There are no fault memory in pcm with that switch i installed.

all the materials i got from work. The valve was from a bmw 335 muffler. The piping size is 2.25" and there is no point going any bigger in my case, since the valve is about 2 to 2.25".

very interesting idea. cool write up too

I'd like to see someone do this with FI

i got a 08 328 in the driveway.......hmmmmm...

*grabs sawzall*:Kill1:

but for real, what year 335, maybe I can grab one from a junk yard. I think this would respond nicely when the nitrous is going

How about a DIY... Maybe I'll do this also.
So the 335's come with butterfly valve on the muffler? Is it for the same reason you did this?

you could also just put a cut out after the cat but then you would have raspiness galore....actually thinking about doin this to mine ...deff agree with posting DIY

All 335(E90, E92) comes with that valve, lot of other bmw models have a valve for the exhaust too, but i think the one on 335 is the biggest 2~2.25". I think it's more for sound and then performance. The valve is on the driver side exhaust tip, go check it out when u see a 335 next time.

Well, i just happen to have one of those valve, so i just want to see if i can make it work. and it seems to be working well. Only problem i m having is, since it's winter and have lot of snow here. I found sometimes after i park it outside for a while, when i start the car again the dump valve would be froze most likely due to all the snow melted on it from the last drive, but after about 2~3mins, once the exhaust heat up a bit, the valve works normal again. not really that big of a deal for me, but maybe i will make some kind of shield for it.....when i have time.

what kind of diy do you guys want? coz it's mostly welding and cutting. i will try to get some more pic next time i have the car up in the air

and then just run a long vacuum hose from the front to the valve on the exhaust.

Then to control the solenoid, when engine is running, one of the pin on the solenoid will have battery voltage(connector is only 2pins). The other wire goes from solenoid to pcm. The solenoid turns on when pcm apply ground which then turns on the vfad and in my case also my dump. All i did to keep the valve close is put a switch between the wire from the solenoid to pcm. When switch is open, the circuit is open so solenoid will not turn on.

I pick to put a switch on the ground wire, becoz it's safer since it's after the load (solenoid). So if my wiring ever broke, or shorted to ground, it's not going to burn the car down, just the solenoid wouldn't work right. since i have to run the wires from engine bay into the inside of the car.

I thought about putting relay in there, have 3 different switch positions, one position is just keep the valve always close at all time, one is let it function by the pcm(open after 5500rpm), one is just open all the time. But then it will be lot of wiring, and i wouldnt' get into it.

The easiest way to have the exhaust valve open all the time, is just unplug the vacuum hose. becoz vacuum keeps the valve close, without the vacuum, valve wont' close.

Sounds like a two-stroke.

my friend says it sounds like a 2 stroke dirt bike on steroid

Nice Job, don't listen to the haters.

Updated with new pic on my first post.