Smog system on '66 w/289
 

I have a 1966 GT Fastback with a 289 and 4V carb. The original smog system is intact and working except for one part. This one part is what I am curious about. In the shop manual its called a "anti-backfire valve". It is mounted on the intake manifold behind the carb. Can anyone tell me what the effects would be if this part is defective? Also, can anyone tell me where I can find a "new" replacement for this part?
Any help would be greatly appreciated.

TC

you don't need it, you have a classic car, so just rip all of your smog stuff off. On the plus side of this, you should gain a small amount of power. just my two cents

What happens to the originality of the vehicle once you remove this equipment? Doesn't it lose some of it's value if the original equipment is missing? I've been told to keep it especially since the car still has to pass a safety check every year. They still look to see if the smog equipment is still working and intact.