Bought a 1994 rx7 that has a m2 airbox but the valves are not connected to it and has a hose to bypass them . Would it cause anything to go wrong ? Should I leave it as it is?

 

For those that liked the sound, it was common to have the blow-off valve vent to atmosphere. No real harm but IIRC the spring in the stock valve wasn't as strong as most aftermarkets and some unfiltered air could get by at idle. The CRV I would leave plugged in to the airbox. I can't think of anything to be gained by leaving it off.
Throw up a picture or two to be certain we're on the same page.

 

 

I'd plug the CRV and, if you like the sound, leave the BOV venting to atmosphere. Just understand there is, IMO, some risk of unfiltered air entering the intake tract. You can use a rubber chair leg cover to cover the unused upper port on the intake box. Measure it, but IIRC 7/8" fits.

 

As others have said, no problems leaving them as is. The crv will vent until the secondary turbo comes on and of course the acv will vent between shifts............ or the other way around. Anyway, leaving them both vented gives you "whooshing" sounds as you build boost until the secondary turbo comes, then when you shift. Vented or recirc, no real difference either way.