03 evo: intake buschur cat back exhaust, apexi air/fuel controller, upgraded fmic, and walbro 255 fuel pump 264/264 hks cams. so heres the question right now i have a vent-to-atmosphere apexi bov. ive heard from quite a few people since my last question that i would be better off using an evo IX diverter valve. i was wondering if you guys could help me with some reasons on why this is so. i dont have any of stallin or rough idle issues ive heard about but am looking for a more reliable daily driver and have heard that a dv is much better in this area. can anyone explain the pros and cons of switching from a vta bov vs. a dv? any help would be greaty appreciated

 

Not sure where your information is coming from. The purpose of getting an aftermarket BOV is to attain higher peak boost and stop the leaking of the stock BOV. How much boost are you running or plan to run?

 

honestly im not looking at running any high boost maybe a hold boost at like 21 and peak at 25. alot of people have just been sayin that vent to atmosphere are useless because the diverter valve helps recirculate boost. but idk as a daily driver im not looking for huge boost gain i just want it to be reliable. i see you use forge i really heard they work amazing. truth or myth?

 

If its not leaking and drives fine, I see no reason to change it.

 

sounds stupid of me to say but thats probably the best damn advice ive gotten from this forums

 

+1 ..If it's not broken, don't fix it.. just hope for a forced upgrade in your near future

 

Ok we all know the stock 03-05 plastic diverter is going to leak around 8 psi. The stock 9 diverter will not leak at the boost pressure your going to push, a good aftermarket solution would be the APS twin vent.

Con the earlier model evo's 03-04 can't really compensate for running VTA this will lead to a few problem: stalling, ruff idle, or bad fuel economy....also part throttle boost the car is going to buck around.

Pro there is no pro to VTA when running stock ECU. If you have the stock ECU and MAF then the 9 diverter or even better would be the APS Twin vent which operates better then the stock 9.

 

Run the metal IX DV...slightly crushed.

 

does the Evo 9 BOV (stock one) leak at 26psi?