this old model hks sequential blow off was on the car when i bought it, see the bolt at the back, will the noise change if i do it up?

 

Nope, the bolt at the back is pressure release setting. The noise is changed (on the new ones, anyway) by replacing the metal-looking deely inside.
Or that's it AFAIK, anywy

 

cheers nom

 

just found this ,so i think ill leave it alone
Q: I installed a blow off valve, it sounds really cool but my car stalls when I let off. Why?

A: First of all, the reason this is happening is because the Air Flow Meter on our cars measures
the air coming in through the flapper door. It senses this air and adjusts the fuel mixture accordingly. When you let big rush of air out of the intake system, you are letting out a bunch of air that was just measured. The fueling will still dump the fuel associated with that air and cause an over rich condition. This will cause your car to stall momentarily or in some cases actually turn off. Once the BOV has closed and the intake system will return to it's normal state and work again.

To fix this, you need to adjust your BOV. Most BOVs have a screw or nut to adjust the tension. You can turn the screw/nut to the right and increase the tension. Do this several times with a test drive in between. If your BOV stops letting out the pressure, you have adjusted it too tight. You will then need to start adjusting soft again. You must keep playing with this adjustment until you get it just right. A good adjustment will allow the BOV to release pressure after slight boost, and not stall afterwards. It is not necessary for the BOV to release pressure when you rev the car.