So, yes, you too have heard that mufflers don't make "that" much difference, right?
Well, in this instance, they made a HUGE difference. The test vehicle was my '00 Jackal with 66k miles.
First, take a look at the dyno sheet shown here.
The RED dyno lines represent the first run using a 525mV T.P.S. setting, K&N filter drop-in, stock mufflers with a Stucchi 'H' type cross-over.
The BLUE dyno lines represent the second run with the SAME t.p.s. settings/K&N, same 'H' pipe x-over, and my Bub "custom" mufflers - a version of the Conti Reps.
Now the max. figures may not be that impressive of gains... but if you look at the usable powerband, you'll see HUGE improvements. At 4k rpm you see a gain of nearly 13 ft./lbs. of torque, and 12 h.p. - and hold to nearly 5.5k rpm, where the stock mufflers slowly close back in. Gains that your "butt dyno" also sure do feel.
The Bub's filled the dip in the midrange spectacularly. This is what I suspected, so I'm happy to see such an impressive spread between the two.
While the total/overall gains are minimal 61.4 hp vs. 64.3 hp, and 56.2 ft/lbs vs. 61.5 ft/lbs it's the meat of the midrange that makes you really grin.
For final results, be sure to check out "More EV Power", which shows the final Power Commanded outcome, and all recommend mods for your Cal based motor.
Todd<at>GuzziTech.com