September 1, 2011
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WHAT IS IT? An easy 2.6-horsepower modification for the 2011-12 KTM 450SXF. This pipe kicked our KTM 450SXF up to almost 57 horsepower.

WHAT’S IT COST? $999.99 (Ti-4R); $779.95 (T4-R stainless); $779.95 (T4).

CONTACT? or (951) 738-8050.

WHAT STANDS OUT? Here’s a list of things that stand out with the 2011-12 Pro Circuit Ti-4R KTM 450SXF exhaust.

(1) Models. The Ti-4R is a top-of-the-line titanium exhaust system; it comes with a welded Ti end cap, Ti canister, resonance chamber, no spark arrestor, extra packing material and a three-piece design. The T4-R system is the exact same exhaust system, but it is constructed out of stainless steel (with an aluminum canister). Pro Circuit’s T-4 is a stainless/aluminum system with a removable spark arrestor, extra packing, resonance chamber and stainless end cap.

(2) Target. The stock 2011 KTM 450SXF has a luscious powerband. It is smooth and easy to ride. The powerband starts down low and builds power incrementally as the rpm increases. It is a do-it-all style of power. But, not every rider is looking for ease of use. Some MXA test riders wanted the 450SXF to hit harder in the middle and rev faster on top?and that is exactly what the Pro Circuit Ti-4R did for the KTM 450SXF. With extra power, the test riders had more usable power?and they had it from the middle on up.

(3) Horsepower. The Pro Circuit exhaust system produced an impressive 56.86 horsepower at peak (compared to 54.21 for the stock pipe). Below 8000 rpm, the stock pipe and Pro Circuit pipe are about equal. But once the power blasts into the midrange, the Pro Circuit exhaust takes over. At 8500 rpm, the Pro Circuit pipe makes one horsepower more than stock. At 9000 rpm, it makes two horsepower more. At 10,000 rpm, it makes two-and-a-half horsepower more. At this point, the stock exhaust system’s power output starts to drop off, while the Pro Circuit pipe hangs on?and the horsepower difference at 10,500 rpm is almost four horsepower more. In essence, the all-new Pro Circuit KTM 450SXF pipe matches the steady roll-on power of the stock KTM, but  pumps up the middle and rips on top.

(4) Performance. Going fast in motocross is more about what the rider can do with the power than how much power he has. MXA‘s hope was that the Pro Circuit exhaust would give the stock powerband a caffeinated burst in the meat of the curve. It did?and it was noticeable, usable and racier. This is mostly a top-end exhaust system that adds lots of mid and up power, but doesn’t add or subtract anything down low.

(5) Bells and whistles. The Ti-4R system is full Ti?including the end cap?and comes with a resonance chamber in the head pipe to make the decibels a tad lower. Most MXA test riders would opt for the stainless steel T4-R system, instead of the $220 more expensive titanium version. Pro Circuit includes a repacking kit with every Ti-4R, T4-R and T4 exhaust system.

WHAT’S THE SQUAWK? Our biggest complaint was that to remove the stock KTM exhaust system, we had to unbolt the shock and drop the shock linkage to get KTM’s one-piece head/mid-pipe out of the frame. After that hassle, the three-piece Pro Circuit system was a snap to install and remove.

Who would have thought a few years ago that a local racer could own a 57-horsepower race bike? That’s works-bike territory and a works-like powerband.


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