Ford says the 2011 Mustang 5.0, which has the new high feature 5.0-liter V-8, makes 412 horsepower at 6500 rpm and 390 pound-feet of torque at 4250 rpm. Perhaps more impressive is the claimed output of the new 3.7-liter V-6 Mustang: 305 horsepower at 6500 rpm and 280 pound-feet at 4250 rpm.

To call Ford's bluff, we took both vehicles to our dyno shop of record, the research and development department at K&N Air Filters in Riverside, California.  Why K&N? Because we use them all the time and love the professional operation they run. Oh, and we dig inertia-type dynamometers.

Inertia-type dynos, like K&N's Dynojets, use large, heavy rollers that employ a 4800-pound roller capable of measuring 1200 horsepower at each axle and measure the rate at which the drivetrain can accelerate them. This type is better for determining horsepower of high-output vehicles, as the power is measured directly. (Torque is mathematically calculated using engine rpm data recorded from a spark signal wire).

Fifth gear for both the Mustang 5.0 and V-6 is 1.00:1, which is typically ideal for dyno pulls because less torque multiplication (or overdrive reduction) lowers the load on the gear teeth and reduces losses. These gears proved too tall, so we dropped down to fourth and third gear and made several runs. K&N's policy is to select the median of three consistent runs, so here is what we came up with:

2011 Mustang 5.0

3rd gear (1.69:1)
Horsepower: 365.26 hp @ 6600 rpm
Torque: 335.27 lb ft @ 4500 rpm

4th gear (1.32:1)
Horsepower: 377.99 hp @ 6500 rpm
Torque: 351.44 lb-ft @ 4400 rpm

2011 Mustang V-6

3rd gear (1.67:1)
Horsepower: 268.06 hp @ 6700 rpm
Torque: 249.95 lb-ft @ 4000 rpm

4th gear (1.24:1)
Horsepower: 267.11 hp @ 5800 rpm
Torque: 259.90 lb-ft @ 4100 rpm

Now here is where it gets interesting. Those numbers are what the V-8 and V-6 Mustangs are putting down at the rear wheels, without factoring in anywhere from 10-25 percent of output lost to friction. Motor Trend's tech department recommendation is a bit more conservative 15 percent.  After examining the power peaks, K&N's techs suggested we use the fourth gear pulls for the 5.0-liter and third gear pulls for 3.7-liter.  With that we arrive at what we think are the most correct output figures for the 2011 Mustangs:

2011 Mustang 5.0 (4th gear pull, 15% powertrain loss)
Claimed horsepower: 412 hp @ 6500 rpm
Claimed torque: 390 lb-ft @ 4250 rpm
Actual horsepower: 435 hp 6500 rpm
Actual torque: 404 lb-ft @ 4400 rpm

2011 Mustang V-6 (3rd gear pull, 15% powertrain loss)
Claimed horsepower: 305 hp @ 6500 rpm
Claimed torque: 280 lb-ft @ 4250 rpm
Actual horsepower: 308 hp @ 6700 rpm
Actual torque: 287 lb-ft @ 4000 rpm

Bottom line? Both cars over deliver on both power and torque. The Mustang 5.0 is certainly the most impressive with 435 horsepower - if you can believe it, that figure put its well over the top of both the Camaro SS and Challenger SRT-8.  Even though the difference between Ford's claim and what we discovered is not as great, the Mustang V-6's output is no less impressive - especially when you consider its claimed 31 mpg on the highway.

Of course, the best news we discovered on Friday we can only hint at.  We believe those dyno figures just have to be accurate, given the outrageous numbers these two 'Stangs threw down at our test track.  But you'll have to check back with us bright and early Monday morning to find those out...

-With Frank Markus

This article originally appeared on Car News Gossip.