Is fitting a BOV to a UK Spec bad?

Just read the following in the Supra Glossary:

Cons:

If you have a UK car, an atmospheric BOV can confuse the ECU because they use a MAF airflow sensor which is ahead of the BOV. This sensor registers that a certain amount of air is flowing in, so the ECU reacts accordingly by supplying the correct amount of fuel. That air then gets vented by the BOV, so the engine runs very rich. This creates two problems – one, the car may stall if the throttle doesn’t come back on, two, if the throttle does come back on the ECU is trying to compensate for an over-richness and may lean the mix off to undesirable levels, potentially causing detonation.

The j spec cars have a manifold pressure sensor and don't suffer from this problem.

Is it really that dangerous?

Dangerous, maybe not, but it will effect the afr

And it will sound shit.

But as above not dangerous.

If I remember correctly, you can fit the HKS BOV with the recirc kit to a UK car.

As stated above. Do not fit a vent to atmosphere due to the MAF.....it's the same on the later VVTi model engines.

I'm assuming a re circ won't make a noise ?

A stock recirc valve makes a lovely and really satisfying sound with an induction kit imo, I assume a recirc bov will just be louder