recirculated is a better BOV, but doesnt make that whoosh noise. Vented does make the whoosh noise but interferes with your MAF readings and so your ecu assumes to put more fuel into the car making it run rich.You normally see vented for cars running more than 30 psi or using aftermarket turbines. Side effects may include stalling, bad idle, and loss of power.


EDIT: Just stick with the OEM bov for your evo, if anything get an intake.

 

I got APS also and it sounds great and no problems

 

All your asking for is trouble with a vent to atmosphere bov. Definetely use a recirculating one.You,ll have idle and stalling problems most likely with a vent valve.

 

Do not use a VTA BOV. Use a recirculating type. The MAF setup on EVOS has problems with Vent To Atmosphere ones.

Also check the threads for intakes, you will find intakes do not provide any increase, and have problems with the car running lean or rich at different rpms due to the intake turbulence through the MAF.

Keep the stock intake and replace the filter with a good panel like K&N or other brand.

Also the stock EVO 8 plastic BOV tends to leak from the housing, so replacing it with a IX or one of the Forge ones will cure the flutter problems. While you are at it, replace the IC hose clampswith t-bolt ones from the turbo all the way to the TB. Amazing how small leaks add up to 4 psi lost quickly.

Milburn