There is a caveat to every exhaust pipe test: Don’t be too enamored with big dyno numbers. The dyno is just a tool that allows us to gauge the shape of the curve and see some comparative figures, but it does not go to the starting line with us. What really counts isn’t which pipe makes the biggest numbers, but which pipe has the most usable power, quickest rev, most throttle response and best power curve. Plus, during testing, we discovered that riders of different skill levels preferred different types of powerbands. The favorite pipe of the Pro test riders wasn’t always the first choice of the Novices, while the Intermediates always seemed to seek the middle ground. You have to have an inner dialogue with yourself about what you really want from a pipe.

8 IMPORTANT TEST FACTS

(1) We tested the exhaust pipes as they were sent to us, and we asked each company to send us the pipe they wanted us to test. This requirement didn’t matter with the stock, DR.D or Scalvini pipes, since they only have one pipe, but Pro Circuit and FMF offer several different models. We were sent the FMF Fatty pipe and the Pro Circuit Works pipe.

(2) We ran each exhaust pipe with its companion silencer (although there was one exception to this rule—because the aftermarket silencer was a major detriment to performance).

(3) The supplied silencers varied in length from 12 inches (FMF and Pro Circuit) to 14.75 inches (DR.D) to 15.5-inches (Scalvini) to 19 inches stock (YZ250).

(4) We sound tested every pipe combo, but since every one easily passed the AMA Amateur 94 dB and AMA Pro 115 dB tests, we didn’t waste time reporting the results. The two smallest silencers were the loudest, but both FMF and Pro Circuit offer longer and quieter silencers for offroad riding.

(5) We dynoed three of the four aftermarket pipes on the same dyno at the same temperature on a brand-new 2013 Yamaha YZ250 and within a three-hour time window to ensure accuracy. Actually we dyno’ed all of them on the same day at the same time, but Scalvini came back later with a new design and asked us to retest it—so, even though it blew the straight across comparison, we agreed to retest this pipe—but have reported the variations in the test copy. We ran 91-octane pump gas and Yamalube R premix.

(6) We raced the bike with numerous test riders over the course of several months and used blind round-robin tests with four different test riders—a Pro, a Vet Pro, an Intermediate and a Novice.

(7) We never let the test riders talk to each other during test sessions.

(8) These are our results. It is important to note that this test applies to most YZ250 two-strokes made over the last half decade regardless of their year of manufacture. The best Yamaha YZ250 pipe for you is in here. Find it.

STOCK YAMAHA

As production pipes go, the stock YZ250 pipe is well made but lacks the niceties of a racing exhaust. The stock YZ250 exhaust pipe has a very solid delivery off the bottom. It has a torquey feel and offers good control between the throttle and the rear wheel. It’s at its best from low to mid, although it does have a chuggy feel when the power valve opens that makes the engine go “brupp, brupp, brupp.” After the irritating little stutter, the stock exhaust pulls into the middle and makes competitive power until around 7000 rpm, where it starts to flatten out. That flatness is the biggest negative of the stock YZ250 exhaust, because from 7000 to 8500 rpm, it just lays there until there is a little kick before sign-off.

HOW DO YOU GET THE MOST OUT OF THIS PIPE?
To get the most out of the stock YZ250 exhaust pipe, you need to short-shift early and try to pull the next gear while keeping the rpm in the meaty part. This isn’t easy to do and requires not only one more tooth on the rear sprocket, but a touch of clutch to keep it on the pipe.

WHAT WAS THE MOST COMMON TEST RIDER COMMENT?
“It’s all bottom and mid, but there is nothing on top. If you over-rev it, the power goes flat. Shift points are crucial if you want to carry speed with this pipe.”

WHO WOULD LIKE THIS PIPE?
No one (if they had the option of choosing from the other four pipes in this test). It ranked either last or next to last on every rider’s evaluation sheet.

STOCK YZ250 DYNO NUMBERS
Here are the stock 2014 Yamaha YZ250 dyno numbers.
rpm                 horsepower
5000……………21.81
6000…………..30.95
7000…………..39.61
8000…………..44.32
9000…………..45.92
Peak…………….46.85 @ 8700 rpm

DURATION ABOVE 44 HORSEPOWER
The stock YZ250 exhaust pipe breaks 44 horsepower at 7900 rpm and stays there until 9100 rpm. The stock YZ250 pipe has a 1200 rpm range above the four-four.

RETAIL PRICE
$280.49 (pipe), $393.49 (silencer).

CONTACT INFO
Your local Yamaha dealer.

DR.D NS2

Without a doubt, the DR.D pipe produced the most power on the front side of the curve. Whereas the other pipes in this shootout had trouble matching the stock YZ250 exhaust at the low end of the rpm scale, the DR.D was strong from the get-go. It mated its good low end with a very strong and pronounced midrange that blew not only the stocker away, but all the other pipes as well. The DR.D pipe was very aggressive at tip-in, out of corners or in quick transitions from left to right. The downside of all that awesome midrange was that the DR.D pipe went flat at 8000 rpm. This was 1000 rpm higher than the stock pipe, but 1000 rpm lower than Pro Circuit.

HOW DO YOU GET THE MOST OUT OF THIS PIPE?
Since it is capable of pulling the next gear, which the stock pipe can’t do, you need to short-shift, and then use the strong midrange to pull the bike like a tractor as opposed to a plow horse. If you keep it around 7000 rpm, it makes 1 to 2 horse-power more than any other pipe. Go above 8000 rpm and it goes flat.

WHAT WAS THE MOST COMMON TEST RIDER COMMENT?
“It pulled very hard in the middle and was powerful enough to run a gear high, but it didn’t want to rev.”

WHO WOULD LIKE THIS PIPE?
This is a gun-and-run pipe that is untouchable in the hands of a rider who knows how to milk the midrange. A rev ranger will not get the most out of this pipe.

DR.D NS2 DYNO NUMBERS
Here are DR.D’s dyno numbers (with the stock YZ250 horsepower in parentheses).
rpm                horsepower            difference
5000……………20.76 (21.81)……………-1.05
6000……………31.33 (30.95)……………+0.38
7000……………41.57 (39.61)……………+1.94
8000……………47.34 (44.32)……………+3.02
9000……………42.88 (45.92)……………-3.04

PEAK HORSEPOWER BY BRAND & RPM
1. Pro Circuit…..49.33 @ 8600 rpm
2. FMF…………..47.71 @ 8700 rpm
3. DR.D…………47.44 @ 7900 rpm
4. Scalvini……..49.80 @ 7800 rpm (not comparable)
5. Stock YZ……46.85 @ 8700 rpm

MAX TORQUE BY BRAND & RPM
1. DR.D………….32.17 ft-lbs @ 7500 rpm
2. FMF……………31.90 ft-lbs @ 7800 rpm
3. Scalvini………32.84 ft-lbs @ 7800 rpm (not comparable)
4. Pro Circuit……31.67 ft-lbs @ 7800 rpm
5. Stock YZ……..30.33 ft-lbs @ 7600 rpm

DURATION ABOVE 44 HORSEPOWER
The DR.D NS2 exhaust pipe breaks 44 horsepower at 7300 rpm and stays there until 8800 rpm. The FMF pipe has a 1500 rpm range above the four-four.

RETAIL PRICE
$239.95 (NS2 pipe), $139.95 (silencer).

CONTACT INFO
www.dubachracing.com or (877) 382-2241.

PRO CIRCUIT WORKS

Make no mistake, this was the most powerful YZ250 exhaust pipe in this test. It was the only one with not only more over-rev, but more ponies on top. It was the only pipe to crack 49 horsepower. In fact, it was the only pipe to crack 48 horsepower. Pro Circuit gets more power by giving up low and mid in exchange for top. Below 7600 rpm, the Pro Circuit pipe is just average, or worse than average. After 7600 rpm, it has no equal. This makes it very exciting to race with, but you give up rideability below the surge. In slow-speed corners, off-cambers and hard-pack, the rider has to practice patience.

HOW DO YOU GET THE MOST OUT OF THIS PIPE?
You pull the trigger. In loam, sand or deeply disced dirt, the Pro Circuit pipe absolutely flies; but, as dirt quality degrades, you have to wait for your chance to unleash the ponies. This pipe works best when it is wide open. This is the classic two-stroke tradeoff: you can’t have both bottom and top. Pick your poison.

WHAT WAS THE MOST COMMON TEST RIDER COMMENT?
“This is a conundrum pipe. You want to run it because it is undoubtedly the fastest pipe, but it’s at its fastest when the conditions suit it. It’s a mid-and-up pipe only.”

WHO WOULD LIKE THIS PIPE?
This is a Pro pipe. It works best in the wheelhouse of talented riders who are capable of carrying speed.

PRO CIRCUIT WORKS DYNO NUMBERS
Here are Pro Circuit’s dyno numbers (with the stock YZ250 horsepower in parentheses).
rpm                  horsepower              difference
5000……………21.43 (21.81)……………-0.38
6000……………30.49 (30.95)……………-0.46
7000……………39.67 (39.61)……………+0.06
8000……………47.78 (44.32)……………+3.46
9000……………45.71 (45.92)……………-0.21

PEAK HORSEPOWER BY BRAND & RPM
1. Pro Circuit..49.33 @ 8600 rpm
2. FMF…………..47.71 @ 8700 rpm
3. DR.D…………47.44 @ 7900 rpm
4. Scalvini……..49.80 @ 7800 rpm (not comparable)
5. Stock YZ……46.85 @ 8700 rpm

MAX TORQUE BY BRAND & RPM
1. DR.D………….32.17 ft-lbs @ 7500 rpm
2. FMF……………31.90 ft-lbs @ 7800 rpm
3. Scalvini………32.84 ft-lbs @ 7800 rpm (not comparable)
4. Pro Circuit…31.67 ft-lbs @ 7800 rpm
5. Stock YZ……..30.33 ft-lbs @ 7600 rpm

DURATION ABOVE 44 HORSEPOWER
The raw metal Pro Circuit Works exhaust pipe breaks 44 horsepower at 7400 rpm and stays there until 9000 rpm. The Pro Circuit pipe has a 1600 rpm range above the 44 horsepower mark.

RETAIL PRICE
$249.95 (Works pipe), $119.5 (R-304 Shorty).

CONTACT INFO
www.procircuit.com or (951) 738-8050.

FMF FATTY

The FMF Fatty is Baby Bear’s porridge. It’s not as good on the bottom as the stock YZ250 pipe. It’s not as good in the middle as the DR.D pipe. And, it’s not as good on top as the Pro Circuit pipe. But, and this is a big but, it is the pipe that puts all the pieces together. It doesn’t make the best power in any of the three ranges (low, mid or top), but it never falls below second in any of those categories, making it an excellent all-around pipe. Whereas the other pipes excel at one thing, the FMF pipe is good at everything. Because of this everyman powerband, it feels like it has the meatiest and most usable power. If it has a flaw, it is that it goes flat at the exact same rpm as the DR.D and Scalvini pipes, leaving the upper stratosphere to Pro Circuit. Every test rider wished for more boost on top.

HOW DO YOU GET THE MOST OUT OF THIS PIPE?
The FMF Fatty doesn’t require any tricks. You don’t have to short-shift. You don’t have to play gun-and-run, and you don’t have to wait for the hit. You just ride it. That’s a compliment on the grandest scale.

WHAT WAS THE MOST COMMON TEST RIDER COMMENT?
“It was the easiest one to keep on the pipe. It didn’t fall off if you shifted too soon or revved too high. It had a full-feeling powerband.”

WHO WOULD LIKE THIS PIPE?
This pipe bridges all the MXA test rider skill categories. It was ranked either first or second by the AMA Pro, Vet Pro, Intermediate and Novice test riders.

FMF FATTY DYNO NUMBERS

Here are FMF’s dyno numbers (with the stock YZ250 horsepower in parentheses).
rpm                    horsepower            difference
5000……………21.25 (21.81)…………….-0.56
6000……………30.69 (30.95)……………-0.26
7000……………40.33 (39.61)……………+0.72
8000……………47.33 (44.32)……………+3.01
9000……………45.09 (45.92)……………-0.92

PEAK HORSEPOWER BY BRAND & RPM
1. Pro Circuit…..49.33 @ 8600 rpm
2. FMF………….47.71 @ 8700 rpm
3. DR.D…………47.44 @ 7900 rpm
4. Scalvini………49.80 @ 7800 rpm (not comparable)
5. Stock YZ…….46.85 @ 8700 rpm

MAX TORQUE BY BRAND & RPM
1. DR.D………….32.17 ft-lbs @ 7500 rpm
2. FMF…………..31.90 ft-lbs @ 7800 rpm
3. Scalvini………32.84 ft-lbs @ 7800 rpm (not comparable)
4. Pro Circuit……31.67 ft-lbs @ 7800 rpm
5. Stock YZ……..30.33 ft-lbs @ 7600 rpm

DURATION ABOVE 44 HORSEPOWER
The FMF Fatty exhaust pipe breaks 44 horsepower at 7400 rpm and stays there until 9000 rpm. The FMF pipe has a 1600 rpm range above 44 horsepower.

RETAIL PRICE
$229.99 (Fatty pipe), $129.99 (Shorty silencer).

CONTACT INFO
www.fmfracing.com or (310) 631-4363.

SCALVINI CONE

The Italian-built Scalvini was the most unique pipe in MXA’s YZ250 exhaust shootout. First, it was the only cone pipe we tested. Second, it was the most expensive. Third, we didn’t like the first pipe they gave us—it didn’t fit or perform very well. when they ask us to test a newer version, we agreed because the new model was the pipe they would be selling from that point on. Every test rider came back impressed by how fluid the new Scalvini made the power feel. It never suffered in the horsepower department on the front side, but gave up some over-rev on top. It was easy to ride, very smooth from gear to gear and a big improvement over the Scalvini YZ250 pipe we tested in 2013.

HOW DO YOU GET THE MOST OUT OF THIS PIPE?
You have to take advantage of the smooth power delivery. This is a pipe that you ride harder in the midrange and shift at peak, which is 8600 rpm. This was almost 1000 rpm higher than their 2103 pipe.

WHAT WAS THE MOST COMMON TEST RIDER COMMENT?
“Very good power, picked up clean off the bottom and felt stronger than stock through the meat of the powerband. One caveat, the best performance from the Scalvini pipe comes when it is mated to the stock YZ250 silencer. When we ran the Scalvini’s carbon fiber silencer the power peaked 500 rpm earlier and gave up almost 4 horsepower to our best combination at 9000 rpm.”

WHO WOULD LIKE THIS PIPE?
Riders with very little two-stroke experience, Novices and Vets would love this pipe. In fact, made the bike easy to ride and was liked best by our Novice and Vet test iders—not so much by the high rpm loving Pros.

SCALVINI DYNO NUMBERS
Here are Scalvini’s dyno numbers (with the stock YZ250 horsepower in parentheses). It is important to note that we dyno tested the new Scalvini pipe at a later date (and both the Scalvini and stock pipe produce better numbers on that day and bike than on the other pipe dyno runs). For example, the stock pipe made 48.64 horsepower and 31.41 foot-pounds of torque at these later dates, compared to 46.85 horsepower and 30.33 foot-pounds of torque. Thus, it is most important to look at the plus and minus gains/losses in the dyno numbers, not the actual numbers. These numbers are direct comparisons between Scalvini and the stock pipe. These numbers are not comparable to the other aftermarket pipes. It should also be noted that with the Scalvini silencer installed we lost over 3 horsepower at 9000 horsepower—so these dyno numbers are with the stock silencer. We do not recommend the Scalvini silencer.

rpm                 horsepower                difference
5000……………22.38 (22.98)…………..-0.60
6000……………32.08 (31.95)……………+0.13
7000……………41.88 (41.53)…………….+0.35
8000……………48.11 (46.40)……………+1.71
9000……………46.63 (46.80)……………-0.17

PEAK HORSEPOWER BY BRAND & RPM
1. Pro Circuit…..49.33 @ 8600 rpm
2. FMF……………47.71 @ 8700 rpm
3. DR.D………….47.44 @ 7900 rpm
4. Scalvini…….49.80 @ 8600 rpm (read above)
5. Stock YZ………46.85 @ 8700 rpm

MAX TORQUE BY BRAND & RPM
1. DR.D………….32.17 ft-lbs @ 7500 rpm
2. FMF……………31.90 ft-lbs @ 7800 rpm
3. Scalvini……..32.84 ft-lbs @ 7800 rpm (read above)
4. Pro Circuit……31.67 ft-lbs @ 7800 rpm
5. Stock YZ……..30.33 ft-lbs @ 7600 rpm

DURATION ABOVE 44 HORSEPOWER
The Scalvini exhaust pipe breaks 44 horsepower at 7200 rpm and stays there until 9100 rpm. The Scalvini has a 1900 rpm range above the four-four.

RETAIL PRICE
$329.00 (pipe), $175.00 (silencer aluminum/carbon), $229.00 (silencer all carbon).

CONTACT INFO
(909) 608-0082 or www.scalvinipipes.com