Street car, some drag racing...

Worth the time or not?

Not really.. if you run mufflers they will restrict
the flow.. basically if you have 5" of HG that will
cause you to have a back pressure so it would be a
negative

I put mufflers on my Duster several years ago so I blocked mine off and mounted catch cans “breather” on each side.

Probably not. Not unless you have some kind of low tension ring package. They rely on the exhaust flow at WOT to work best. Driving on the street is probably not going to do a lot to evacuate the engine. Mufflers of any kind reduce how well the system works. Vacuum pumps seem to be more popular now.

No IMO. I have a vacuum pump on my hemi and don't care for it really (never really saw a gain from it). My wedge has two -10 lines, one from each valve cover, to a breather tank. I like that setup much better.

Good info, thanks guys

Depends on the muffler, and where you put the muffler.

I run them on my street car, just after the muffler and they work.

We pulled the collectors, with the evac tubes, off of a set of open headers, and installed a pair of Borla collector mufflers with evac tubes installed in them. The system did not work nearly as well. Not even close.

I wouldn't mess with that stuff for a street car. On a drag car I'd use a vacuum pump. I do not see any reason for the old school evac tube set up anymore. That was what we used 40 years ago before vacuum pumps were invented.

Unless you get a GREAT deal on a vacuum pump there are way better ways to gain horsepower. And even if you get a deal there are good vacuum pumps and JUNK vacuum pumps.