91 xr7... problem i would see with a check valve would be that even at atmospheric pressure the bypass would close so unless it was capable of locking in vac it wouldn't work, i assumed you were talking about a one way pressure valve
But seriously if a mid 15 sec car is to fast she shouldnt be driving!
You can't, it's to slow already, comes from the factory like that.
remove the blower belt !!
Coming from somebody that drives an LX.
-Corey
Taking the belt off would just make the car run like crap. Air just isnt meant to run just through the bypass or the "Spinning by air" rotors of the SC. Opening up the bypass is one way and installing a larger sc pulley as had bene mentioned from a late model SC is another.
But seriously if a mid 15 sec car is to fast she shouldnt be driving!
I'm thinking today, you don't do anything and you install the Drivecam system so you can Trust, but Verify. It's not cheap, but if you have American Family insurance you can get it for free.