Depends on which BOV you plan to run.
If you use a BOV that sports a 1" inlet (the port that goes to your IC piping),
Then you can get away with using the stock port, with a short 1" hose and clamps.
If you decide to use an HKS SSQV, TiAL (FTW), or most of the GReddy BOV's that require an actual flange, then you'll need to be welding a flange to the IC piping, and the BOV will be strapped onto that.
What a lot of people do since 7M-GTE's run factory, with a recirculated Blow off Valve, Is...
Run a larger more appropriate BOV that's actually flanged onto the IC pipe, and then run a Bosch 103/110 (whichever it may be) in place of the factory one. Running a Bosch 110 BOV (which recirculates) will help with rich AFR's in between shifts.
This keeps the car from going uber rich when you come to a quick stop or shifting in between shifts, and prevents stalling & backfiring.
**ON A PERSONAL NOTE**
I've ran the HKS SSQV, TurboXS RFL, Bosch 110 and now the TiAL 50mm...
And I must say...
Once you got TiAL, there's no going back. :biglaugh:
With a handfull of boost (15+psi), this thing sounds amazing.
It's not ear piercing loud like a SSQV, but it has a very intimidating and 'head-turning' type of sound to it. Sounds amazing, and more importantly, will hold anything you throw at it.
It's a beast...especially with an 11psi spring.
-Jeff