i installed a muse o2 dump and a new catch can setup at the same time...-10 fittings in valve cover etc...went for a 3rd and 4th gear pull and car hits 28 psi and just tapers down to 22...with the megan o2 housing itll hit 29 psi and hold at 25ish...i thought the o2 dump was supposed to help it with spool and holding boost? car feels slower now...its stock evo 9 turbo, cams, basic bolt ons...i did a boost leak test and everything seemed good unless i missed something...with more exhaust flow engine is more efficient i get that but is it normal for boost to just taper way down like that when it didnt do it before?

 

Sounds normal, anytime you free up a restriction in the exhaust your boost will drop because its running more efficiently

 

you need to be retuned for it...

 

i thought there was no need to retune for an o2 dump...also, its holding just 22 psi to redline when it used to hold 25 ish...isnt that too much of a drop? what if i tighten the preload on the wastegate?

 

You drastically changed the back pressure characteristics of the exhaust system, as well as the total airflow through the engine. Hence the lowered boost. You need to get the car retuned.

 

makes sense...afr got leaner by about .1 - .2 only...by tuning it can it be made to hold more boost to redline?

 

Depends on the tuner, and if you're using an MBC or ECU boost. Also, the stock turbo really shouldn't be made to hold that much boost out the top...

 

I'm using aem boost solenoid controlled by ecu...turbo is healthy...I don't beat on it a lot but when I do I want it to hold more boost...if I tighten the wastegate arm some will it hold more boost?

 

Which o2 housing gasket did you use? The oem gasket or the gasket that seperate the downpipe and dump tube?

 

i got the divorced gasket...bought the copper gasket from english racing i think it was...

 

This. You'll make more power at any given boost level with a dump. Still my favorite mod to this day

 

Wow, thats quite the difference in boost. Goes to show that the dump flows more. ****, looks like I need to stop being a ***** about the noise and get one.

 

My girlfriend hates it when I go wot and take a dump on her

 

You'll love it. And the noise is the best part, especially in a tunnel

 

I have a buddy that has an Evo with an O2 dump. I think I could live with the noise, its not that loud (dumps under the car, not out of the hood). But I did smell some exhaust fumes in the car. Nothing that would bother me, but I don't want my son breathing that in. Is that common with all O2 dumps?