I'm testing a pair of 3" Catco cats, and three 3" race mufflers; the Ultraflow Welded, the Warlock with cut out, and the FlowMaster one-chambered muffler.
        I was faced with a few surprises.

    LOUDNESS:

     No cat on car. The present "bullet" race mufflers quieted the car down slightly, so I un-hooked the actuator arm to make it louder again. Car was put in 1st gear, and brake torqued to 2500 rpm, against the converter. Decibel meter on tripod, about 10 feet away.

        Cat and Ultraflow = 103
        Cat and Flowmaster = 103
        Cat and capped Warlock = 100

        Remember, this is from 10 feet away, and aimed right at the pipe. In reality the 100 decibels of the cat and Warlock was amazingly quiet! Each decibel increases sound intensity by 26%. The 111 decibel reading of the straight pipe was 11 higher than the cat & capped Warlock. 1.26 x 1.26 x 1.26... (11 times, total) makes the open pipe a whopping 12.7 times louder!!

        The straight pipe (111) was 59% louder than with the Ultraflow or the Flowmaster (109 each).
        The straight pipe (111) was 800% louder than the capped Warlock (102).

       LOOKING THROUGH THE UNCAPPED WARLOCK

       WEIGHT:

     FlowMaster =7 lbs
          Ultraflow = 11 lbs
          Warlock = 16 lbs
          Long Catco hi-flo 3" cat  = 6.5 lbs
          2.5" Catco hi-flo cat = 6.5 lbs
          Short hi-flo 3" cat = 6.75 lbs.

        NOTE: the cats all  weigh about the same, in spite of the long 3" cat having a *bigger* body!

       FLOW:

    Flow was tested like this:  A leaf blower directed all of it's flow through each piece, with an ultra sensitive pressure gauge measuring inches of water of back-pressure. Each inch of water is roughly 1/26 of a single psi!
    The little vacuum line barb that picks up the pressure signal from inside the leaf blower's exit tube is affected by the Bernoulli Principle; air rushing past the barb causes a partial vacuum, and registers over 1" water BELOW ZERO. When a 2 foot piece of SS 3" pipe is inserted into the end of the leaf blower, pressure registers ZERO, as the straight pipe adds a *little* back pressure and cancels out the Bernoulli effect.
    Any muffler recording a zero is just like running a straight pipe!!

    Ultraflow = over 1" *below* zero  (You read that right!! The Ultraflow seems to be BETTER than a straight pipe!)
    Warlock uncapped = 0.0"
    FlowMaster = 1.8" water back-pressure
    Short Catco 3" cat = 4.0"
    Long Catco 3" cat = 4.0"
     2.5" Catco hi-flo cat = 4.75"
    Warlock capped = 6.2"

    OK; I can hear you saying, "How can an Ultraflow muffler beat a straight 3" pipe"?  This welded Ultraflow (as opposed to the seamed SS Ultraflows) has a HUGE *4"* PIPE running through it; only the entrance and exit is 3".  The 4" pipe with smooth drilled holes in it flows better than a 3". This is the only muffler I've ever tested that has a shot at REDUCING the back pressure that you get with NO muffler at all, and it actually quiets the car down more than my two 3"  Race Magnum Bullet mufflers (which offer MORE restriction)!!

    PS: The longer "sport" Ultraflow is quieter... 
 

          POINTS

    I don't consider muffler weight to be as important as flow or sound, because the difference from the lightest to the heaviest piece is only 9 lbs, which is less than one one-hundredth in the 1/4 mile. Loudness isn't as important as flow, either. So I gave flow points of 5 for 1st place, 3 for 2nd place, and 1 for third, while giving the other 2 categories 3 for 1st place, 2 for 2nd, and 1 for 3rd.

        Weight = Flowmaster 3, Ultraflow 2, Warlock 1
        Loudness = Warlock 3, Ultraflow and Flowmaster tied for 2 points each
        Flow = Ultraflow 5, uncapped Warlock 3, Flowmaster 1

      FlowMaster = 3, 2, 1, for a total of 6 points
      Warlock = 1,  3, 3, for a total of 7 points
      Ultraflow = 2, 2, 5, for a total of  9 points
 

    Although the FlowMaster lost the competition by one point, remember that it is FAR FAR better flowing than stock, and will never have fiberglass or ceramic wool falling out of it, or burning out. It has it's merits...

        PROS and CONS =
 
 

muffler	PRO	CON
Flowmaster	No fiberglass to burn out	some back pressure
Warlock	Quietest and excellent flow	have to cap and un-cap to reap benefits
Ultraflow	Excellent flow  with no back pressure	fiberglass