Can I put a HKS Blow off valve on my 2002 s60. Where i should put it, and it should blow off the air to the atmosphere or directly to intake pipe????

 

If it's the stock mitsubishi turbo it already has one built in.

 

You can put one on, but I'm not sure you would want to. I installed the eurosport open air element (deletes factory airbox) and got a very nice blowoff valve sound. I later installed the Snabb intake piping and got a slightly louder sound. My BOV sound isn't as loud as one that is vented to the atmosphere, but it is loud enough for me and can easily be heard from outside or inside the car.

In my experience, the blow off valve sound gets old. Plus if you vent to the atmosphere you will run rich which will foul plugs and sometimes cause a little puff of smoke out the tailpipe on some cars.