Originally Posted by techinspector1
When we were kids, we used to go to the boneyard and get gasoline tank filler tubes and caps from old cars. We'd cut into the head pipes and install them, one on each side. The filler caps would twist on or off with 1/2 turn and would work great until the hot exhaust burned the rubber seal out of them. If you were really cool, you had a chrome filler cap showing right behind the front tire on each side.
That's cool but my cutout is even cheaper. Drill a 1 3/4" [or larger if pipe is larger] hole in the pipe where you would do a weld-on. Place a band clamp over the hole to close it. Slide it down the pipe to open it, it's "tuneable".