My Question is Which Blow off valve would work good with My Evo IX MR and I won't lose Boost in?

 

The Stock Ix BOV is fine to 26psi. Otherwise APS twin vent is popular, which is what I was running with my 50trim powered Evo

 

Will this blow off valve do any negative affects to my boost? Because from what i know is that most other blow off valves from other companies don't work so good with the MR?

 

It has nothing to do with the MR. It is just Evos in general that have issues with some BOVs. The MR is exactly the same as the GSR and RS under the hood. The only differences are the MR and RS have alluminium roofs and the GSR does not and the MR has a 6 speed tranny and Bilstein shocks.

The issue with some BOVs is that if they are not Diverter valves or recirculating valves they will cause idle issues and make your car run rich between shifts. I was running a open atmospher BOV for a while and my car was awful to drive. It would stall out if I pressed the clutch in quickly.

The two BOVs I listed above will not have a negitive effect on your car unless you hook them up wrong. The BOV that will Effect boost is the stock 03-05 GSR and RS BOV they are plastic and leak boost pretty badly. Your stock BOV is perfect for your car untill you want to run over 26 PSI or so