WHAT IS IT? The Ti-5 is Pro Circuit’s top-of-the-line titanium exhaust pipe. It features an asymmetrical canister, resonance chamber, two-meter-max certification and your choice of carbon or Ti end caps.

$999.99 (Ti-5 titanium), $779.95 (T-4 stainless/aluminum), $549.95 (Ti-4 titanium slip-on), $424.95 (T-4 stainless/aluminum slip-on).

CONTACT? or (951) 738-8050.

WHAT STANDS OUT? Here’s a list of things that stand out with the 2012 Pro Circuit KX450F exhaust.

(1) Development. Even though Pro Circuit is Kawasaki’s official KX250F team?and has won more AMA Championships than any other private team?they have more than a passing interest in fielding a KX450F team. Historically, they have built full-on race bikes for their riders and for other teams, including Hart & Huntington, the Grand Prix-based Kawasaki CLS team and, up until this season, the official Kawasaki team. They have considerable R&D time with the KX450F.

(2) Performance. In stock trim, the 2012 Kawasaki KX450F engine has an awesome power profile. It’s no secret that the stock KX450F powerband is an arm stretcher that pumps out over 55.50 horsepower. If you asked every MXA test rider if the 2012 Kawasaki KX450F needed an aftermarket exhaust, they would have said no?until they tried Pro Circuit’s Ti-5 carbon exhaust system. Pro Circuit was smart enough not to increase peak power (producing the exact same 55.50 horsepower at 9000 rpm), but what Pro Circuit did do was increase power and torque earlier in the curve (from 5000 rpm to 6500 rpm) and later in the curve (from 9500 rpm to 11,400 rpm). Why was this smart? Because it made the roll-on power easier to use. The Pro Circuit pipe made three horsepower more than the stocker at a lowly 5500 rpm. That extra power smoothed out the low-to-mid transition and made the KX450F easier to ride. Increasing power upwards of three horses down low helped the power blend into the KX’s awesome midrange power more progressively. The second plus to the Pro Circuit Ti-5 was that the added horsepower on the top broadened the power and made the over-rev more usable. In essence, the Ti-5 filled in the KX450F’s bell-shaped curve on both ends, which was exactly what the KX450F needed.

(3) Sound test.
Next year, the AMA and FIM will both test bikes using the two-meter-max system. The two-meter-max test requires bikes to come in under 115 decibels with the throttle held wide open. The Pro Circuit Ti-5 passes the two-meter-max test at exactly 115 decibels. The stock KX450F muffler fails?at an ear-piercing 122 dB.

(4) End cap. When you order a Pro Circuit Ti-5 exhaust system, you can choose between a carbon fiber end cap and a titanium end cap. The price is the same.

(5) Cheaper options. Pro Circuit makes stainless/aluminum systems and slip-ons for riders watching their wallets.

Our complaint with the Pro Circuit pipe has nothing to do with Pro Circuit. Kawasaki designed the KX450F muffler to be held in place by one bolt. This may have worked with two-strokes, but in the age of ultra-long and heavy four-stroke exhaust systems, one bolt is not enough to withstand crash damage.

It’s rare that an exhaust-pipe company builds a pipe that doesn’t increase peak horsepower, but that is exactly what Pro Circuit did with the Ti-5. Instead, they filled in the bottom and the top to beef up the complete powerband.

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