Okay so I have the following mods on my Evo IX MR and I am tuned to run 24 PSI:

- Agency Power TI Exhaust
- Apexi Power Intake
- Titek 3" Downpipe
- Apexi Induction Box
- RRE Rally Cat
- Walbro 255LPH FUel Pump with install kit
- RC 1000cc Injectors
- Sun Auto Hyperforce
- Titek V2 02 Housing
- ETS LICP V2 Steel Black
- GM 3-Port Boost Solenoid
- Custom Dyno Tune

My dyno numbers (Mustang Dyno) are 310 WHP and 299 WTQ for those who are curious, and the car runs very well.. Logged the car a few days ago and no serious counts of knock (mainly 1's, a few 2's; not very many of them either).

Now the only problem is, not really a problem, but its a weird noise coming from my engine bay when I'm going WOT. The only way to describe the sound is that it sounds like my intake is stuttering. I was almost certain that it was my DV (I have the stock metal DV) leaking because I've heard that the stock ones, uncrushed, can hold 23 PSI MAX. But then a friend of mine also said that compressor surge can happen even at partial throttle or full throttle, so could that be it? I was thinking that compressor surge can only happen at off throttle.

Basically, it sounds like fluttering at WOT.

Also, while looking at my boost gauge at WOT, I have the stock MR gauges, the needle fluctuates between 1.4 bar to passed 1.5 bar.. The needle never settles. That's what made me think that my DV was leaking for sure.

Any insight or comments would be greatly appreciated, thanks!

 

That DV should be able to hold 24 psi of boost, mine lasted up to 28 flawlessly. Once I went over the 28 mark it didn't hold and you could hear it releasing the pressure, so I upgraded to the APS TV. With the gauge fluttering and an audible noise though I would say boost leak or the valve might be bad and not holding pressure. I would run a boost leak test and see if you have any leaks, then just upgrade the BOV. If you are going to keep modding youll have to change it out sooner or later...

 

Bump for any more suggestions and/or opinions!

 

I think buchnerj's suggestion is probably the best place to start. Troubleshooting is the only way to find out so you gotta start somewhere. Usually compressor surge occurs because of a faulty BOV/DV so that would be my guess. The stock valve SHOULD be able to hold 24psi, but just because it works on one car doesn't necessarily mean it will work on every car. In my opinion, do what buchnerj posted.