Without starting a huge debate, I will say with all confidence that the best valve both for performance and the money for the RA is going to be an OEM unit off Evo IX MR or the new X series.
- They'll hold the boost you want to run
- They're very inexpensive compared to aftermarket
- They open and close with the same reaction speed as ...well an OEM valve.
The plastic valves are prone to failure as you start to turn up the boost or just over time. This can lead to performance issues associated with your typical boost leak.
Installation is a snap. There are two clamps that need to be undone. You can use either a phillips screw driver or a 10mm socket wrench. Loosen the clamps and slide them back over the two hoses so that they don't fall if/when you need to wrench the valve around to get it off.
Replace the valve in the same direction as the original. Should you install the valve backwards, you will hear an abnormal amount of compressor surge from the turbo. It will sound like a mini helicopter is making a landing on your turbo. If you forget which way the valve goes, just remember the brass hat needs to be facing your hood and not your radiator.
I used a BOV off my old Evo 8 MR. The nipple is facing a slightly different angle. And being the cheap SOB that I am, I did not want to invest 30 cents to buy a new vacuum hose. At any rate, because of this, the line came up slightly short.
You need to make certain that you do not crimp the vacuum line. To avoid this, I pivoted the valve slightly to the left until the hose has a smooth, unobstructed connection.
Slide the hose clamps back on and snug everything down. You don't need to torque the be-jesus out of the clamps. Make sure they're tight, but don't tear the threads on the clamps by over torquing them.
This is a very simple mod that won't break your bank and will support higher performance tuning as you move onward and upward.
Happy Modding!